OCCUSYSTEMS INC
8-K, 1997-05-15
OFFICES & CLINICS OF DOCTORS OF MEDICINE
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<PAGE>

===============================================================================

                          SECURITIES AND EXCHANGE COMMISSION
                               Washington, D.C.  20549



                                      ------------

                                       FORM 8-K
                                    CURRENT REPORT

                           Pursuant to Section 13 or 15(d)
                        of the Securities Exchange Act of 1934

            Date of Report (Date of earliest event reported): May 14, 1997


                                     -------------


                                  OCCUSYSTEMS, INC.
                (Exact name of Registrant as specified in its charter)


         DELAWARE                     0-24440                  75-2543036
    (State or other            (Commission File Number)    (I.R.S. Employer
jurisdiction of incorporation)                           Identification Number)


   3010 LBJ FREEWAY                                               75234
      SUITE 300                                                  (Zip code)
    DALLAS, TEXAS
(Address of principal
  executive offices)      
         
         Registrant's telephone number, including area code:  (972) 484-2700

                                    NOT APPLICABLE
                    (former address if changed since last report)


===============================================================================

<PAGE>



ITEM 5.  OTHER EVENTS

    See the following Registration Statement on Form S-4 (file no. 
333-27105) attached hereto as Exhibit 99.1, dated May 14, 1997, filed by 
Concentra Managed Care, Inc., a Delaware corporation ("Concentra"), with the 
Securities and Exchange Commission in connection with the solicitation of 
proxies by the Board of Directors of OccuSystems, Inc. (the "Company"), and 
the Board of Directors of CRA Managed Care, Inc., a Massachusetts corporation 
("CRA"), for use at special meetings of stockholders of the Company and CRA.  
These special meetings have been called to consider and vote upon, among 
other things, proposals to approve and adopt an Agreement and Plan of Merger 
dated as of April 21, 1997, among the Company, CRA and Concentra pursuant to 
which (a) the Company will merge with and into Concentra with the separate 
corporate existence of the Company ceasing (the "OccuSystems Merger") and (b) 
a wholly-owned subsidiary of Concentra will be merged with and into CRA with 
the separate corporate existence of that subsidiary ceasing (the "CRA 
Merger," together with the OccuSystems Merger, the "Mergers").  The 
Registration Statement relates to the shares of common stock of Concentra 
that are proposed to be issued in connection with the Mergers to the holders 
of common stock of the Company and the holders of common stock of CRA.


ITEM 7.  FINANCIAL STATEMENTS AND EXHIBITS

(c)  EXHIBITS

    99.1      Registration Statement on Form S-4 (file no. 333-27105)
              as filed with the Securities and Exchange Commission on 
              May 14, 1997.

    99.2      Consent of Arthur Andersen LLP










<PAGE>


                                    SIGNATURES


    Pursuant to the requirements of the Securities Exchange Act of 1934, the 
registrant has duly caused this report to be signed on its behalf by the 
undersigned thereunto duly authorized.

                                        OCCUSYSTEMS, INC
                                        (Registrant)



                                        By:/s/ Richard A. Parr II
                                           ---------------------------------
                                        Name:     Richard A. Parr II
                                        Title:    Executive Vice President 
                                                  and General Counsel

Date:    May 14, 1997






<PAGE>


                                  INDEX TO EXHIBITS

EXHIBIT
NUMBER                                                                   PAGE
- -------                                                                  -----
99.1        Registration Statement on Form S-4 (file no. 333-27105)
            as filed with the Securities and Exchange Commission on
            May 14, 1997.     

99.2        Consent of Arthur Andersen LLP




<PAGE>





                                     EXHIBIT 99.1

                             CONCENTRA MANAGED CARE, INC.
                          REGISTRATION STATEMENT ON FORM S-4








<PAGE>
      AS FILED WITH THE SECURITIES AND EXCHANGE COMMISSION ON MAY 14, 1997
                                                      REGISTRATION NO. 333-27105
- --------------------------------------------------------------------------------
- --------------------------------------------------------------------------------
 
                       SECURITIES AND EXCHANGE COMMISSION
 
                             WASHINGTON, D.C. 20549
                           --------------------------
                                    FORM S-4
                             REGISTRATION STATEMENT
                                     UNDER
                           THE SECURITIES ACT OF 1933
                           --------------------------
                          CONCENTRA MANAGED CARE, INC.
             (Exact name of registrant as specified in its charter)
 
<TABLE>
<S>                                   <C>                                   <C>
              DELAWARE                                8093                               04-3363415
  (State or other jurisdiction of         (Primary Standard Industrial                (I.R.S. Employer
   incorporation or organization)         Classification Code Number)               Identification No.)
</TABLE>
 
                                312 UNION WHARF
                          BOSTON, MASSACHUSETTS 02109
                                 (617) 367-2163
    (Address, including zip code, and telephone number, including area code,
                  of registrant's principal executive offices)
                           --------------------------
                                DONALD J. LARSON
                     PRESIDENT AND CHIEF EXECUTIVE OFFICER
                          CONCENTRA MANAGED CARE, INC.
                                312 UNION WHARF
                          BOSTON, MASSACHUSETTS 02109
                                 (617) 367-2163
 (Name, address, including zip code, and telephone number, including area code,
                             of agent for service)
                           --------------------------
                                   COPIES TO:
 
<TABLE>
<S>                              <C>                              <C>
      JEFFREY A. CHAPMAN               RICHARD A. PARR II                  JAMES WESTRA
    Vinson & Elkins L.L.P.          Executive Vice President            Hutchins, Wheeler &
       2001 Ross Avenue                and General Counsel                   Dittmar,
          Suite 3700                    OccuSystems, Inc.           A Professional Corporation
      Dallas, Texas 75201          3010 LBJ Freeway, 6th Floor          101 Federal Street
        (214) 220-7700                 Dallas, Texas 75234          Boston, Massachusetts 02110
                                         (972) 484-2700                   (617) 951-6600
</TABLE>
 
                           --------------------------
    APPROXIMATE DATE OF COMMENCEMENT OF PROPOSED SALE TO THE PUBLIC: As soon as
practicable after the effective date of this Registration Statement.
 
    If the securities being registered on this Form are being offered in
connection with the formation of a holding company and there is compliance with
General Instruction G, check the following box. / /
                           --------------------------
                        CALCULATION OF REGISTRATION FEE
 
<TABLE>
<CAPTION>
                                                                                  PROPOSED MAXIMUM
                           TITLE OF EACH CLASS OF                                    AGGREGATE                 AMOUNT OF
                        SECURITIES TO BE REGISTERED                            OFFERING PRICE (1)(2)        REGISTRATION FEE
<S>                                                                           <C>                       <C>
Common Stock, $.01 par value per share (3)..................................        $923,898,591                $279,969
</TABLE>
 
(1) Based upon the registrant's estimate of the maximum number of shares that
    may be issued in connection with the Mergers described herein. Pursuant to
    Rule 416(a), this Registration Statement covers such additional number of
    shares of Common Stock as may be issued after the Effective Time in
    connection with the antidilution provisions of stock options or stock
    appreciation rights, the underlying securities of which are being registered
    hereby.
(2) Estimated solely for purposes of determining the registration fee in
    accordance with Rule 457(f). Based upon (a) the product of (i) the average
    of the high and low sales prices of shares of common stock, par value $.01
    per share ("OccuSystems Common Stock"), of OccuSystems, Inc. ("OccuSystems")
    on May 8, 1997 ($21.94 per share), times (ii) 25,838,420, which represents
    the sum of (w) the number of shares of OccuSystems Common Stock outstanding
    on May 8, 1997, plus (x) the maximum number of shares of OccuSystems Common
    Stock that are issuable upon exercise of OccuSystems stock options
    outstanding on May 8, 1997, plus (y) the maximum number of shares of
    OccuSystems Common Stock issuable upon conversion of OccuSystems'
    outstanding 6% Convertible Subordinated Notes due 2001, plus (z) the number
    of shares of OccuSystems Common Stock issuable upon conversion of the 6%
    Convertible Promissory Note dated October 1, 1993 issued by OccuSystems to
    John Anderson, D.O., plus (b) the product of (i) the average of the high and
    low sales prices of shares of common stock, par value $.01 per share ("CRA
    Common Stock"), of CRA Managed Care, Inc. ("CRA") on May 8, 1997 ($39.19 per
    share), times (ii) 9,109,560, which represents the sum of (x) the number of
    shares of CRA Common Stock outstanding on May 8, 1997, plus (y) the maximum
    number of shares of CRA Common Stock that are issuable upon exercise of CRA
    stock options outstanding on May 8, 1997.
 
(3) This Registration Statement also covers the associated common share purchase
    rights (the "Rights") and the Series B Junior Participating Preferred Stock,
    par value $.01 per share, issuable upon the exercise of such Rights. Until
    the occurrence of certain prescribed events, the Rights will not be
    exercisable, will be evidenced by the certificates for the Common Stock of
    the Registrant and will be transferred along with and only with such
    certificates. Thereafter, separate certificates will be issued representing
    one Right for each share of Common Stock of the Registrant, subject to
    adjustment for dilution.
                           --------------------------
    THE REGISTRANT HEREBY AMENDS THIS REGISTRATION STATEMENT ON SUCH DATE OR
DATES AS MAY BE NECESSARY TO DELAY ITS EFFECTIVE DATE UNTIL THE REGISTRANT SHALL
FILE A FURTHER AMENDMENT WHICH SPECIFICALLY STATES THAT THIS REGISTRATION
STATEMENT SHALL THEREAFTER BECOME EFFECTIVE IN ACCORDANCE WITH SECTION 8(A) OF
THE SECURITIES ACT OF 1933, AS AMENDED, OR UNTIL THE REGISTRATION STATEMENT
SHALL BECOME EFFECTIVE ON SUCH DATE AS THE COMMISSION, ACTING PURSUANT TO SAID
SECTION 8(A), MAY DETERMINE.
 
- --------------------------------------------------------------------------------
- --------------------------------------------------------------------------------
<PAGE>
                           [INSERT OCCUSYSTEMS LOGO]
 
                                                                          , 1997
 
To the Stockholders of OccuSystems, Inc.:
 
    You are cordially invited to attend a Special Meeting of Stockholders (the
"OccuSystems Meeting") of OccuSystems, Inc. ("OccuSystems"), to be held on
      , 1997, at 10:00 a.m., Dallas time, at the Holiday Inn, 4441 Highway 114
and Esters Boulevard, Irving, Texas 75063.
 
    At the OccuSystems Meeting, you will be asked to approve the merger (the
"OccuSystems Merger") of OccuSystems with and into Concentra Managed Care, Inc.,
a Delaware corporation ("Concentra"), in conjunction with the merger of CRA
Merger Corp., a Massachusetts corporation and wholly-owned subsidiary of
Concentra, with and into CRA Managed Care, Inc., a Massachusetts corporation
("CRA"), pursuant to an Agreement and Plan of Reorganization dated as of April
21, 1997 (the "Reorganization Agreement").
 
    Upon completion of these mergers:
 
    - Concentra will be the surviving corporation of the OccuSystems Merger and
      the separate corporate existence of OccuSystems will cease;
 
    - CRA will become a wholly-owned subsidiary of Concentra;
 
    - each outstanding share of OccuSystems Common Stock will be converted into
      one share of Concentra Common Stock; and
 
    - each outstanding share of CRA Common Stock (other than shares held by
      holders who have perfected appraisal rights) will be converted into 1.786
      shares of Concentra Common Stock.
 
    If the mergers are approved, you will also be asked to approve the Concentra
1997 Long-Term Incentive Plan (the "Concentra Incentive Plan") and the Concentra
Employee Stock Purchase Plan (the "Concentra Employee Stock Purchase Plan" and,
together with the Concentra Incentive Plan, the "Concentra Benefit Plans"). The
mergers contemplated by the Reorganization Agreement are not conditioned on
approval of the Concentra Incentive Plan or the Concentra Employee Stock
Purchase Plan.
 
    A detailed description of the Reorganization Agreement, the proposed mergers
of OccuSystems and CRA, the Concentra Incentive Plan and the Concentra Employee
Stock Purchase Plan is set forth in the accompanying Joint Proxy
Statement/Prospectus, which you should read carefully.
 
    After careful consideration, your Board of Directors has determined that the
transactions contemplated by the Reorganization Agreement are in the best
interests of the stockholders of OccuSystems. Accordingly, the Board has
unanimously approved the Reorganization Agreement and the OccuSystems Merger and
recommends that all OccuSystems stockholders vote for approval thereof. The
Board of Directors has also unanimously approved the Concentra Benefit Plans and
recommends that all OccuSystems stockholders vote for their approval.
 
    YOUR VOTE IS IMPORTANT. FAILURE TO VOTE OR TO RETURN YOUR PROXY CARD WILL
HAVE THE SAME EFFECT AS A VOTE AGAINST THE REORGANIZATION AGREEMENT AND THE
OCCUSYSTEMS MERGER. THEREFORE, WHETHER OR NOT YOU PLAN TO ATTEND THE OCCUSYSTEMS
MEETING IN PERSON AND REGARDLESS OF THE NUMBER OF SHARES YOU OWN, I URGE YOU TO
COMPLETE, SIGN AND DATE THE ENCLOSED PROXY CARD AND RETURN IT IN THE ENCLOSED
ENVELOPE AS SOON AS POSSIBLE. You may, of course, attend the OccuSystems Meeting
and vote in person, even if you have previously returned your proxy card.
 
                                        Sincerely yours,
 
                                        John K. Carlyle
                                        CHAIRMAN OF THE BOARD
                                        AND CHIEF EXECUTIVE OFFICER
 
                             YOUR VOTE IS IMPORTANT
                    PLEASE SIGN, DATE AND RETURN YOUR PROXY
<PAGE>
                           [INSERT OCCUSYSTEMS LOGO]
                            ------------------------
 
                   NOTICE OF SPECIAL MEETING OF STOCKHOLDERS
                                        , 1997
                            ------------------------
 
    A Special Meeting of Stockholders (the "OccuSystems Meeting") of
OccuSystems, Inc., a Delaware corporation ("OccuSystems"), will be held starting
at 10:00 a.m., Dallas time, on       , 1997, at the Holiday Inn, 4441 Highway
114 and Esters Boulevard, Irving, Texas 75063. Attendance at the OccuSystems
Meeting will be limited to stockholders of record on       , 1997, or their
proxies, beneficial owners having evidence of ownership on such date and invited
guests of OccuSystems.
 
    The purposes of the OccuSystems Meeting are:
 
        1.  To consider and vote upon a proposal (the "OccuSystems Proposal") to
    approve and adopt (i) an Agreement and Plan of Reorganization dated as of
    April 21, 1997 (the "Reorganization Agreement"), by and among OccuSystems,
    CRA Managed Care, Inc., a Massachusetts corporation ("CRA"), and Concentra
    Managed Care, Inc., a Delaware corporation ("Concentra"), and (ii) the
    merger of OccuSystems with and into Concentra pursuant to the Reorganization
    Agreement (the "OccuSystems Merger"). The Reorganization Agreement
    contemplates, among other things, that (a) OccuSystems will be merged with
    and into Concentra and a wholly-owned subsidiary of Concentra will be merged
    with and into CRA, resulting in CRA becoming a wholly-owned subsidiary of
    Concentra, (b) each outstanding share of common stock, par value $.01 per
    share ("OccuSystems Common Stock"), of OccuSystems will be converted into
    one share of common stock, par value $.01 per share ("Concentra Common
    Stock"), of Concentra, and (c) each outstanding share of common stock, par
    value $.01 per share, of CRA (other than shares held by holders who have
    perfected appraisal rights) will be converted into 1.786 shares of Concentra
    Common Stock.
 
        2.  To consider and vote upon a proposal to approve the adoption of the
    Concentra 1997 Long-Term Incentive Plan (the "Concentra Incentive Plan"),
    the terms of which are described in the accompanying Joint Proxy
    Statement/Prospectus. The full text of the Concentra Incentive Plan is
    included as Appendix G to the Joint Proxy Statement/Prospectus.
 
        3.  To consider and vote upon a proposal to approve the adoption of the
    Concentra Employee Stock Purchase Plan (the "Concentra Employee Stock
    Purchase Plan"), the terms of which are described in the accompanying Joint
    Proxy Statement/Prospectus. The full text of the Concentra Employee Stock
    Purchase Plan is included as Appendix H to the Joint Proxy
    Statement/Prospectus.
 
        4.  To transact such other business as may properly come before the
    OccuSystems Meeting or at any adjournments or postponements thereof.
 
    The terms of the OccuSystems Proposal, the Concentra Common Stock to be
issued in connection therewith, the Concentra Incentive Plan and the Concentra
Employee Stock Purchase Plan are described in detail in the accompanying Joint
Proxy Statement/Prospectus. To ensure that your vote will be counted, please
complete, date and sign the enclosed proxy card and return it promptly in the
enclosed postage-paid envelope, whether or not you plan to attend the
OccuSystems Meeting. You may revoke your proxy in the manner described in the
accompanying Joint Proxy Statement/Prospectus at any time before it is voted at
the OccuSystems Meeting.
 
    In the event that there are not sufficient votes to approve the OccuSystems
Proposal, the Concentra Incentive Plan or the Concentra Employee Stock Purchase
Plan, it is expected that the OccuSystems Meeting will be postponed or adjourned
in order to permit further solicitation of proxies by OccuSystems.
 
    Holders of record of shares of OccuSystems Common Stock at the close of
business on       , 1997, the record date for the OccuSystems Meeting, are
entitled to notice of and to vote at the OccuSystems Meeting or at any
postponements or adjournments thereof. The affirmative vote of the holders of a
majority of the outstanding shares of OccuSystems Common Stock is required to
approve the OccuSystems Proposal. The affirmative vote of the holders of a
majority of the total combined shares present and eligible to vote at the
OccuSystems Meeting and a meeting of CRA stockholders (after giving effect to
the
<PAGE>
exchange ratio to be applied in the Mergers) is required to approve the
Concentra Incentive Plan and the Concentra Employee Stock Purchase Plan.
 
                                          By order of the Board of Directors
                                          Richard A. Parr II
                                          Executive Vice President, General
                                          Counsel
                                          and Secretary
 
Dallas, Texas
 
      , 1997
 
                                   IMPORTANT
 
    WHETHER OR NOT YOU PLAN TO ATTEND THE OCCUSYSTEMS MEETING IN PERSON, PLEASE
COMPLETE, SIGN, DATE AND RETURN THE ENCLOSED PROXY CARD AS SOON AS POSSIBLE. A
RETURN ENVELOPE IS PROVIDED FOR YOUR CONVENIENCE. YOU MAY REVOKE YOUR PROXY AT
ANY TIME BEFORE IT IS VOTED BY DELIVERING TO THE SECRETARY OF OCCUSYSTEMS AT
3010 LBJ FREEWAY, SUITE 400, DALLAS, TEXAS 75234, A SIGNED NOTICE OF REVOCATION
OR A LATER DATED SIGNED PROXY CARD OR BY ATTENDING THE OCCUSYSTEMS MEETING AND
VOTING IN PERSON.
 
          DO NOT SEND IN ANY STOCK CERTIFICATES WITH YOUR PROXY CARD.
<PAGE>
                               [Insert CRA Logo]
 
                                                                          , 1997
 
To the Stockholders of CRA Managed Care, Inc.:
 
    You are cordially invited to attend a Special Meeting of Stockholders (the
"CRA Meeting") of CRA Managed Care, Inc. ("CRA"), to be held on       , 1997, at
10:00 a.m., Boston time, at the offices of Hutchins, Wheeler & Dittmar, 101
Federal Street, Boston, Massachusetts 02110.
 
    At the CRA Meeting, you will be asked to approve the merger (the "CRA
Merger") of CRA Merger Corp., a Massachusetts corporation ("CRA Merger Corp.")
and a wholly-owned subsidiary of Concentra Managed Care, Inc., a Delaware
corporation ("Concentra"), with and into CRA in conjunction with the merger of
OccuSystems, Inc., a Delaware corporation ("OccuSystems"), with and into
Concentra pursuant to an Agreement and Plan of Reorganization dated as of April
21, 1997 (the "Reorganization Agreement").
 
    Upon completion of these mergers:
 
    - CRA will become a wholly-owned subsidiary of Concentra;
 
    - Concentra will be the surviving corporation of the merger with OccuSystems
      and the separate corporate existence of OccuSystems will cease;
 
    - each outstanding share of CRA Common Stock (other than shares held by
      holders who have perfected appraisal rights) will be converted into 1.786
      shares of Concentra Common Stock; and
 
    - each outstanding share of OccuSystems Common Stock will be converted into
      one share of Concentra Common Stock.
 
    If the mergers are approved, you will also be asked to approve the Concentra
1997 Long-Term Incentive Plan (the "Concentra Incentive Plan") and the Concentra
Employee Stock Purchase Plan (the "Concentra Employee Stock Purchase Plan" and,
together with the Concentra Incentive Plan, the "Concentra Benefit Plans"). The
mergers contemplated by the Reorganization Agreement are not conditioned on
approval of the Concentra Incentive Plan or the Concentra Employee Stock
Purchase Plan.
 
    A detailed description of the Reorganization Agreement, the proposed mergers
of CRA and OccuSystems, the Concentra Incentive Plan and the Concentra Employee
Stock Purchase Plan is set forth in the accompanying Joint Proxy
Statement/Prospectus, which you should read carefully.
 
    After careful consideration, CRA's Board of Directors has determined that
the transactions contemplated by the Reorganization Agreement are in the best
interests of the stockholders of CRA. Accordingly, the Board has unanimously
approved the Reorganization Agreement and the CRA Merger and recommends that all
CRA stockholders vote for approval thereof. The Board of Directors also
unanimously approved the Concentra Benefit Plans and recommends that all CRA
stockholders vote for their approval.
 
    YOUR VOTE IS IMPORTANT. FAILURE TO VOTE OR TO RETURN YOUR PROXY CARD WILL
HAVE THE SAME EFFECT AS A VOTE AGAINST THE CRA MERGER. THEREFORE, WHETHER OR NOT
YOU PLAN TO ATTEND THE CRA MEETING IN PERSON AND REGARDLESS OF THE NUMBER OF
SHARES YOU OWN, I URGE YOU TO COMPLETE, SIGN AND DATE THE ENCLOSED PROXY CARD
AND RETURN IT IN THE ENCLOSED ENVELOPE AS SOON AS POSSIBLE. You may, of course,
attend the CRA Meeting and vote in person, even if you have previously returned
your proxy card.
 
                                  Sincerely yours,
 
                                  Donald J. Larson
 
                                  PRESIDENT AND CHIEF EXECUTIVE OFFICER
 
                             YOUR VOTE IS IMPORTANT
                    PLEASE SIGN, DATE AND RETURN YOUR PROXY
<PAGE>
                               [INSERT CRA LOGO]
                            ------------------------
 
                   NOTICE OF SPECIAL MEETING OF STOCKHOLDERS
                                        , 1997
                            ------------------------
 
    A Special Meeting of Stockholders (the "CRA Meeting") of CRA Managed Care,
Inc., a Massachusetts corporation ("CRA"), will be held starting at 10:00 a.m.,
Boston time, on       , 1997, at the offices of Hutchins, Wheeler & Dittmar, 101
Federal Street, Boston, Massachusetts 02110. Attendance at the CRA Meeting will
be limited to stockholders of record on       , 1997, or their proxies,
beneficial owners having evidence of ownership on such date and invited guests
of CRA.
 
    The purposes of the CRA Meeting are:
 
        1.  To consider and vote upon a proposal (the "CRA Proposal") to approve
    and adopt (i) an Agreement and Plan of Reorganization dated as of April 21,
    1997 (the "Reorganization Agreement"), by and among CRA, OccuSystems, Inc.,
    a Delaware corporation ("OccuSystems"), and Concentra Managed Care, Inc., a
    Delaware corporation ("Concentra"), (ii) the merger of a wholly-owned
    subsidiary of Concentra into CRA (the "CRA Merger") and (iii) the Agreement
    and Plan of Merger to be entered into by CRA and such subsidiary of
    Concentra in order to effect the CRA Merger. The Reorganization Agreement
    contemplates, among other things, that (a) OccuSystems will be merged with
    and into Concentra and a wholly-owned subsidiary of Concentra will be merged
    with and into CRA, resulting in CRA becoming a wholly-owned subsidiary of
    Concentra, (b) each outstanding share of common stock, par value $.01 per
    share, of OccuSystems will be converted into one share of common stock, par
    value $.01 per share ("Concentra Common Stock"), of Concentra, and (c) each
    outstanding share of common stock, par value $.01 per share, of CRA (other
    than shares held by holders who have perfected appraisal rights) will be
    converted into 1.786 shares of Concentra Common Stock.
 
        2.  To consider and vote upon a proposal to approve the adoption of the
    Concentra 1997 Long-Term Incentive Plan (the "Concentra Incentive Plan"),
    the terms of which are described in the accompanying Joint Proxy
    Statement/Prospectus. The full text of the Concentra Incentive Plan is
    included as Appendix G to the Joint Proxy Statement/Prospectus.
 
        3.  To consider and vote upon a proposal to approve the adoption of the
    Concentra Employee Stock Purchase Plan (the "Concentra Employee Stock
    Purchase Plan"), the terms of which are described in the accompanying Joint
    Proxy Statement/Prospectus. The full text of the Concentra Employee Stock
    Purchase Plan is included as Appendix H to the Joint Proxy
    Statement/Prospectus.
 
        4.  To transact such other business as may properly come before the CRA
    Meeting or at any adjournments or postponements thereof.
 
    The terms of the CRA Proposal, the Concentra Common Stock to be issued in
connection therewith, the Concentra Incentive Plan and the Concentra Employee
Stock Purchase Plan are described in detail in the accompanying Joint Proxy
Statement/Prospectus. To ensure that your vote will be counted, please complete,
date and sign the enclosed proxy card and return it promptly in the enclosed
postage-paid envelope, whether or not you plan to attend the CRA Meeting. You
may revoke your proxy in the manner described in the accompanying Joint Proxy
Statement/Prospectus at any time before it is voted at the CRA Meeting.
 
    In the event that there are not sufficient votes to approve the CRA
Proposal, the Concentra Incentive Plan or the Concentra Employee Stock Purchase
Plan, it is expected that the CRA Meeting will be postponed or adjourned in
order to permit further solicitation of proxies by CRA.
 
    If the CRA Proposal is approved by the CRA stockholders at the CRA Meeting
and the CRA Merger is effected by CRA, any stockholder (1) who files with the
corporation, before the taking of the vote on the CRA Proposal, written
objection to the proposed action stating that such stockholder intends to demand
payment for such stockholder's shares if the action is taken and (2) whose
shares are not voted in favor of such action has or may have the right to demand
in writing from CRA, within twenty days after the date of
<PAGE>
mailing to such stockholder of notice in writing that the corporate action has
become effective, payment for such stockholder's shares and an appraisal of the
value thereof. CRA and any such stockholder shall in such case have the rights
and duties and shall follow the procedure set forth in sections 88 to 98,
inclusive, of chapter 156B of the General Laws of Massachusetts.
 
    Holders of record of shares of CRA Common Stock at the close of business on
      , 1997, the record date for the CRA Meeting, are entitled to notice of and
to vote at the CRA Meeting or at any postponements or adjournments thereof. The
affirmative vote of the holders of two-thirds of the outstanding shares of CRA
Common Stock is required to approve the CRA Proposal. The affirmative vote of
the holders of a majority of the total combined shares present and eligible to
vote at the CRA Meeting and a meeting of OccuSystems stockholders (after giving
effect to the exchange ratio to be applied in the Mergers) is required to
approve the Concentra Incentive Plan and the Concentra Employee Stock Purchase
Plan.
 
                                          By order of the Board of Directors
 
                                          James Westra
                                          Clerk
 
Boston, Massachusetts
      , 1997
 
                                   IMPORTANT
 
    WHETHER OR NOT YOU PLAN TO ATTEND THE CRA MEETING IN PERSON, PLEASE
COMPLETE, SIGN, DATE AND RETURN THE ENCLOSED PROXY CARD AS SOON AS POSSIBLE. A
RETURN ENVELOPE IS PROVIDED FOR YOUR CONVENIENCE. YOU MAY REVOKE YOUR PROXY AT
ANY TIME BEFORE IT IS VOTED BY DELIVERING TO THE CLERK OF CRA AT 312 UNION
WHARF, BOSTON, MASSACHUSETTS 02109, A SIGNED NOTICE OF REVOCATION OR A LATER
DATED SIGNED PROXY CARD OR BY ATTENDING THE CRA MEETING AND VOTING IN PERSON.
 
          DO NOT SEND IN ANY STOCK CERTIFICATES WITH YOUR PROXY CARD.
<PAGE>
OCCUSYSTEMS, INC.                                         CRA MANAGED CARE, INC.
                             JOINT PROXY STATEMENT
 
                            FOR SPECIAL MEETINGS OF
                       STOCKHOLDERS OF OCCUSYSTEMS, INC.
                                      AND
                     STOCKHOLDERS OF CRA MANAGED CARE, INC.
                         TO BE HELD              , 1997
 
                          CONCENTRA MANAGED CARE, INC.
                                   PROSPECTUS
 
    This Joint Proxy Statement/Prospectus is being furnished to holders of
common stock of OccuSystems, Inc., a Delaware corporation ("OccuSystems"), in
connection with the solicitation of proxies by the Board of Directors of
OccuSystems (the "OccuSystems Board") for use at the special meeting of
stockholders of OccuSystems to be held on             , 1997, or any adjournment
or postponement thereof (the "OccuSystems Meeting"), and to holders of common
stock of CRA Managed Care, Inc. a Massachusetts corporation ("CRA"), in
connection with the solicitation of proxies by the Board of Directors of CRA
(the "CRA Board") for use at the special meeting of stockholders of CRA to be
held on             , 1997, or any adjournment or postponement thereof (the "CRA
Meeting" and, together with the OccuSystems Meeting, the "Special Meetings").
 
    The OccuSystems Meeting has been called to consider and vote upon a proposal
(the "OccuSystems Proposal") to approve and adopt (i) an Agreement and Plan of
Reorganization dated as of April 21, 1997 (the "Reorganization Agreement"), by
and among OccuSystems, CRA and Concentra Managed Care, Inc., a Delaware
corporation ("Concentra"), and (ii) the merger of OccuSystems with and into
Concentra pursuant to the Reorganization Agreement (the "OccuSystems Merger").
 
    The CRA Meeting has been called to consider and vote upon a proposal (the
"CRA Proposal") to approve and adopt (i) the Reorganization Agreement, (ii) the
merger of a wholly-owned subsidiary of Concentra with and into CRA pursuant to
the Reorganization Agreement (the "CRA Merger" and, together with the
OccuSystems Merger, the "Mergers") and (iii) the Agreement and Plan of Merger to
be entered into to effect the CRA Merger (the "CRA Merger Agreement").
 
    Stockholders at the Special Meetings will also be asked to consider and vote
upon separate proposals to approve the Concentra 1997 Long-Term Incentive Plan
(the "Concentra Incentive Plan") and the Concentra Employee Stock Purchase Plan
(the "Concentra Employee Stock Purchase Plan" and, together with the Concentra
Incentive Plan, the "Concentra Benefit Plans").
 
    This Joint Proxy Statement/Prospectus also serves as a prospectus of
Concentra with respect to the registration under the Securities Act of 1933 (the
"Securities Act") of up to       shares of common stock, par value $.01 per
share (the "Concentra Common Stock") of Concentra, that will be issued to (i)
holders of outstanding shares of Common Stock, par value $.01 per share (the
"OccuSystems Common Stock"), of OccuSystems, upon consummation of the
OccuSystems Merger and (ii) the holders of outstanding shares of Common Stock,
par value $.01 per share (the "CRA Common Stock"), of CRA, upon consummation of
the CRA Merger. See "THE REORGANIZATION AGREEMENT -- Conversion of OccuSystems
Common Stock" and "-- Conversion of CRA Common Stock."
 
    This Joint Proxy Statement/Prospectus and accompanying form of proxy are
first being mailed to the stockholders of OccuSystems and CRA on or about
            , 1997.
 
    THE SECURITIES TO BE ISSUED PURSUANT TO THIS JOINT PROXY
STATEMENT/PROSPECTUS HAVE NOT BEEN APPROVED OR DISAPPROVED BY THE SECURITIES AND
EXCHANGE COMMISSION OR ANY STATE SECURITIES COMMISSION NOR HAS THE SECURITIES
AND EXCHANGE COMMISSION OR ANY STATE SECURITIES COMMISSION PASSED UPON THE
ACCURACY OR ADEQUACY OF THIS JOINT PROXY STATEMENT/PROSPECTUS. ANY
REPRESENTATION TO THE CONTRARY IS A CRIMINAL OFFENSE.
 
    SEE "RISK FACTORS AND CERTAIN CONSIDERATIONS" BEGINNING ON PAGE 17 OF THIS
JOINT PROXY STATEMENT/PROSPECTUS FOR A DISCUSSION OF CERTAIN RISKS THAT SHOULD
BE CONSIDERED IN CONNECTION WITH YOUR DECISION ON WHETHER TO VOTE FOR THE
MERGERS.
 
    The date of this Joint Proxy Statement/Prospectus is             , 1997.
<PAGE>
                               TABLE OF CONTENTS
<TABLE>
<CAPTION>
                                                    PAGE
                                                    -----
<S>                                              <C>
AVAILABLE INFORMATION..........................           3
INCORPORATION OF CERTAIN DOCUMENTS BY
  REFERENCE....................................           4
SUMMARY........................................           5
  The Companies................................           5
  The Special Meetings.........................           5
  The Reorganization Agreement.................           6
  The Stock Option Agreements..................           9
  The Mergers..................................           9
SUMMARY HISTORICAL AND PRO FORMA FINANCIAL
  INFORMATION..................................          12
COMPARATIVE PER SHARE DATA.....................          15
  Comparative Market Prices and Dividends......          15
  Quotation of Concentra Common Stock..........          16
RISK FACTORS AND CERTAIN CONSIDERATIONS........          17
  Cautionary Statement Regarding
    Forward-Looking Information................          17
  Fixed Merger Consideration...................          17
  Uncertainties Relating to Combination of
    Businesses.................................          17
  No Prior Public Market; Possible Volatility
    of Stock Price.............................          18
  Pending Accounting Developments..............          18
  Material Benefits to Insiders................          18
THE SPECIAL MEETINGS...........................          19
  Times and Places; Purposes...................          19
  Voting Rights, Votes Required for Approval...          19
  Proxies......................................          20
THE MERGERS....................................          23
  Background of the Mergers....................          23
  Recommendation of OccuSystems Board;
    OccuSystems' Reasons for the Mergers.......          26
  Recommendation of CRA Board; CRA's Reasons
    for the Mergers............................          27
  Opinions of Financial Advisors...............          29
  Interests of Certain Persons in the
    Mergers....................................          35
  Accounting Treatment.........................          37
  OccuSystems Notes............................          38
  Certain Federal Income Tax Consequences......          38
  Regulatory Approvals.........................          39
  Quotation of Concentra Common Stock..........          40
  Resale Restrictions..........................          40
  Dissenters' Rights...........................          40
THE REORGANIZATION AGREEMENT...................          41
  The Mergers..................................          41
  Conversion of OccuSystems Common Stock.......          41
  Conversion of CRA Common Stock...............          42
  Certain Representations and Warranties.......          43
  Certain Covenants............................          43
  Conditions to the Mergers....................          48
  Termination of the Reorganization
    Agreement..................................          48
  Termination Fees.............................          49
THE STOCK OPTION AGREEMENTS....................          49
  General......................................          49
  Certain Repurchases..........................          50
  Voting.......................................          50
  Limitation on Total Profit...................          51
  Standstill Provisions........................          51
  Restrictions on Transfer.....................          52
BUSINESS OF OCCUSYSTEMS........................          53
BUSINESS OF CRA................................          54
BUSINESS OF CONCENTRA..........................          55
 
<CAPTION>
                                                    PAGE
                                                    -----
<S>                                              <C>
  General......................................          55
  New Credit Facility..........................          55
COMPARATIVE PER SHARE MARKET PRICE AND DIVIDEND
  INFORMATION..................................          56
CAPITALIZATION.................................          57
PRO FORMA FINANCIAL INFORMATION................          58
COMPARISON OF STOCKHOLDERS' RIGHTS.............          62
  Comparison of Stockholders' Rights with
    Respect to Concentra and OccuSystems.......          62
  Comparison of Stockholders' Rights with
    Respect to Concentra and CRA...............          62
DESCRIPTION OF CONCENTRA CAPITAL STOCK.........          66
  Authorized Capital Stock.....................          66
  Common Stock.................................          66
  Preferred Stock..............................          66
  Stockholder Rights Plan......................          67
  Convertible Subordinated Notes...............          69
  Transfer Agent and Registrar.................          69
  Certain Antitakeover Effects of Concentra
    Certificate, Concentra Bylaws and Delaware
    Law........................................          69
MANAGEMENT OF CONCENTRA........................          71
  Directors....................................          71
  Officers.....................................          73
  Compensation of Executive Officers...........          74
DESCRIPTION OF THE CONCENTRA 1997 LONG-TERM
  INCENTIVE PLAN...............................          75
  General......................................          75
  Awards.......................................          76
  Other Provisions.............................          77
  Tax Implications of Awards...................          78
DESCRIPTION OF THE CONCENTRA EMPLOYEE STOCK
  PURCHASE PLAN................................          80
  General......................................          80
  Offering Dates...............................          81
  Purchase Price...............................          81
  Purchase of Stock; Exercise of Option........          81
  Other Provisions.............................          82
  Federal Income Tax Consequences..............          82
SECURITY OWNERSHIP OF OCCUSYSTEMS, CRA AND
  CONCENTRA....................................          84
  OccuSystems..................................          84
  CRA..........................................          85
  Concentra....................................          86
LEGAL MATTERS..................................          87
EXPERTS........................................          87
FUTURE STOCKHOLDER PROPOSALS...................          87
The Reorganization Agreement....................  Appendix A
OccuSystems, Inc. Stock Option
  Agreement.....................................  Appendix B
CRA Managed Care, Inc. Stock Option
  Agreement.....................................  Appendix C
Opinion of Donaldson, Lufkin & Jenrette
  Securities Corporation........................  Appendix D
Opinion of Alex. Brown & Sons
  Incorporated..................................  Appendix E
The CRA Merger Agreement........................  Appendix F
The Concentra Incentive Plan....................  Appendix G
The Concentra Employee Stock
  Purchase Plan.................................  Appendix H
Sections 86 to 98 of Massachusetts Business
  Corporation Law...............................  Appendix I
</TABLE>
 
                                       2
<PAGE>
    NO PERSON HAS BEEN AUTHORIZED TO GIVE ANY INFORMATION OR MAKE ANY
REPRESENTATION NOT CONTAINED OR INCORPORATED BY REFERENCE INTO THIS JOINT PROXY
STATEMENT/PROSPECTUS AND, IF SO GIVEN OR MADE, SUCH INFORMATION OR
REPRESENTATION MUST NOT BE RELIED UPON AS HAVING BEEN AUTHORIZED. THIS JOINT
PROXY STATEMENT/PROSPECTUS DOES NOT CONSTITUTE AN OFFER TO SELL OR A
SOLICITATION OF AN OFFER TO BUY ANY SECURITIES OTHER THAN THOSE TO WHICH IT
RELATES OR AN OFFER TO SELL OR A SOLICITATION OF AN OFFER TO BUY ANY SECURITIES
IN ANY JURISDICTION IN WHICH, OR TO ANY PERSON TO WHOM, IT IS UNLAWFUL TO MAKE
SUCH OFFER OR SOLICITATION. NEITHER THE DELIVERY OF THIS JOINT PROXY
STATEMENT/PROSPECTUS NOR THE SALE OF ANY SECURITIES HEREUNDER SHALL, UNDER ANY
CIRCUMSTANCES, CREATE AN IMPLICATION THAT THERE HAS BEEN NO CHANGE IN THE
AFFAIRS OF OCCUSYSTEMS OR CRA SINCE THE DATE HEREOF OR THAT THE INFORMATION
HEREIN IS CORRECT AS OF ANY TIME SUBSEQUENT TO ITS DATE.
 
                             AVAILABLE INFORMATION
 
    OccuSystems and CRA are each subject to the informational requirements of
the Securities Exchange Act of 1934 (the "Exchange Act"), and in accordance
therewith each files reports, proxy statements and other information with the
Securities and Exchange Commission (the "Commission"). Such reports, proxy
statements and other information filed with the Commission can be inspected and
copied at the public reference facilities maintained by the Commission at Room
1024, 450 Fifth Street, N.W., Judiciary Plaza, Washington, D.C. 20549 and at the
following Regional Offices of the Commission: Citicorp Center, 500 West Madison
Street, Suite 1400, Chicago, Illinois 60661 and 7 World Trade Center, Suite
1300, New York, New York 10048. Copies of such material can be obtained at
prescribed rates from the Public Reference Section of the Commission at 450
Fifth Street, N.W., Judiciary Plaza, Washington, D.C. 20549. The Commission
maintains a Web site that contains reports, proxy and information statements and
other information regarding registrants that file electronically with the
Commission that is located at http:// www.sec.gov. OccuSystems Common Stock and
CRA Common Stock are quoted on The Nasdaq National Market and such material may
also be inspected at the offices of The Nasdaq Stock Market, Inc., Listing
Section, 1735 K Street, N.W., Washington, D.C. 20006.
 
    Concentra has filed with the Commission a registration statement on Form S-4
(together with all amendments, exhibits and schedules thereto, the "Registration
Statement") under the Securities Act of 1933 (the "Securities Act"), relating to
shares of Concentra Common Stock that are proposed to be issued in connection
with the Mergers to holders of OccuSystems Common Stock and CRA Common Stock.
See "THE REORGANIZATION AGREEMENT -- Conversion of OccuSystems Common Stock" and
"-- Conversion of CRA Common Stock." This Joint Proxy Statement/Prospectus does
not contain all of the information set forth in the Registration Statement filed
by Concentra with the Commission, certain portions of which are omitted in
accordance with the rules and regulations of the Commission. Such additional
information is available for inspection and copying at the offices of the
Commission. Statements contained in this Joint Proxy Statement/Prospectus or in
any document incorporated into this Joint Proxy Statement/Prospectus by
reference as to the contents of any contract or other document referred to
herein or therein are not necessarily complete, and in each instance reference
is made to the copy of such contract or other document filed as an exhibit to
the Registration Statement or such other document, each such statement being
qualified in all respects by such reference.
 
                                       3
<PAGE>
                INCORPORATION OF CERTAIN DOCUMENTS BY REFERENCE
 
    The following documents previously filed by OccuSystems with the Commission
under the Exchange Act are incorporated herein by reference:
 
    (a) OccuSystems' Annual Report on Form 10-K for the fiscal year ended
December 31, 1996 (the "OccuSystems Form 10-K");
 
    (b) OccuSystems' Quarterly Report on Form 10-Q for the quarter ended March
31, 1997 (the "OccuSystems Form 10-Q"); and
 
    (c) OccuSystems' Current Report on Form 8-K dated April 21, 1997
(collectively with the OccuSystems Form 10-K and the OccuSystems Form 10-Q, the
"OccuSystems Reports").
 
    The following documents previously filed by CRA with the Commission under
the Exchange Act are incorporated herein by reference:
 
    (a) CRA's Annual Report on Form 10-K for the year ended December 31, 1996
(the "CRA Form 10-K"); and
 
    (b) CRA's Quarterly Report on Form 10-Q for the quarter ended March 31, 1997
(collectively with the CRA Form 10-K, the "CRA Reports").
 
    All documents filed by OccuSystems or CRA pursuant to Sections 13(a), 13(c),
14 or 15(d) of the Exchange Act after the date of this Joint Proxy
Statement/Prospectus and prior to the date of the Special Meetings shall be
deemed to be incorporated by reference into this Joint Proxy
Statement/Prospectus and to be a part hereof from the date of filing of such
documents.
 
    Any statement contained in a document incorporated or deemed to be
incorporated by reference herein or contained in this Joint Proxy
Statement/Prospectus shall be deemed to be modified or superseded for purposes
hereof to the extent that a statement contained herein (or in any other
subsequently filed document that is or is deemed to be incorporated by reference
herein) modifies or supersedes such previous statement. Any statement so
modified or superseded shall not be deemed to constitute a part hereof except as
modified or superseded.
 
    All information contained or incorporated by reference in this Joint Proxy
Statement/Prospectus relating to OccuSystems has been supplied by OccuSystems
and all such information relating to CRA has been supplied by CRA.
 
    THIS JOINT PROXY STATEMENT/PROSPECTUS INCORPORATES DOCUMENTS BY REFERENCE
THAT ARE NOT PRESENTED HEREIN OR DELIVERED HEREWITH. THESE DOCUMENTS (OTHER THAN
EXHIBITS TO SUCH DOCUMENTS UNLESS SUCH EXHIBITS ARE SPECIFICALLY INCORPORATED BY
REFERENCE HEREIN) ARE AVAILABLE, WITHOUT CHARGE, UPON ORAL OR WRITTEN REQUEST BY
ANY PERSON TO WHOM THIS JOINT PROXY STATEMENT/PROSPECTUS HAS BEEN DELIVERED, IN
THE CASE OF DOCUMENTS RELATING TO OCCUSYSTEMS, FROM OCCUSYSTEMS, 3010 LBJ
FREEWAY, SUITE 400, DALLAS, TEXAS 75234, ATTENTION: RICHARD A. PARR II,
EXECUTIVE VICE PRESIDENT AND GENERAL COUNSEL; TELEPHONE NUMBER (972) 484-2700,
AND IN THE CASE OF DOCUMENTS RELATING TO CRA, FROM CRA, 312 UNION WHARF, BOSTON,
MASSACHUSETTS 02109, ATTENTION: JEFFREY R. LUBER, SENIOR COUNSEL; TELEPHONE
NUMBER (617) 367-2163. IN ORDER TO ENSURE TIMELY DELIVERY OF THE DOCUMENTS PRIOR
TO THE SPECIAL MEETINGS, ANY SUCH REQUEST SHOULD BE MADE BY            , 1997.
 
                                       4
<PAGE>
                                    SUMMARY
 
    THE FOLLOWING SUMMARY IS INTENDED ONLY TO HIGHLIGHT CERTAIN INFORMATION
CONTAINED ELSEWHERE IN THIS JOINT PROXY STATEMENT/PROSPECTUS. THIS SUMMARY IS
NOT INTENDED TO BE COMPLETE AND IS QUALIFIED IN ITS ENTIRETY BY THE MORE
DETAILED INFORMATION CONTAINED ELSEWHERE IN THIS JOINT PROXY
STATEMENT/PROSPECTUS, THE APPENDICES HERETO AND THE DOCUMENTS INCORPORATED BY
REFERENCE OR OTHERWISE REFERRED TO HEREIN. STOCKHOLDERS OF OCCUSYSTEMS AND CRA
ARE URGED TO REVIEW THIS ENTIRE JOINT PROXY STATEMENT/PROSPECTUS CAREFULLY,
INCLUDING THE APPENDICES HERETO AND SUCH OTHER DOCUMENTS REFERRED TO HEREIN.
 
THE COMPANIES
 
    OCCUSYSTEMS.  OccuSystems is the nation's largest physician practice
management company focusing on occupational healthcare. OccuSystems currently
manages the practices of 204 physicians in OccuSystems' 118 occupational
healthcare centers located in 32 markets in 16 states. OccuSystems provides the
management, facilities, administrative and technical support, case management,
physical therapy services and other ancillary services necessary to establish
and maintain a fully integrated network of occupational healthcare providers.
OccuSystems believes that this network of physicians and facilities combined
with OccuSystems' management expertise and cost containment programs provide
significant advantages to patients, employers, physicians and payors in reducing
the overall costs associated with occupational healthcare. Since December 1,
1991, OccuSystems has acquired the assets of 113 physician practices and
developed 27 physician practices. OccuSystems' executive offices are located at
3010 LBJ Freeway, Suite 400, Dallas, Texas 75234 and its telephone number is
(972) 484-2700. See "BUSINESS OF OCCUSYSTEMS."
 
    CRA.  CRA provides field case management and specialized cost containment
services designed to reduce workers' compensation costs. CRA operates one of the
largest field case management organizations in North America, consisting of 119
field case management offices with approximately 1,200 field case managers who
provide medical management and return to work services in 49 states, the
District of Columbia and Canada. CRA also provides a broad range of higher
margin specialized cost containment services from 78 service locations,
including utilization management, specialized preferred provider organization
("PPO") network management, telephonic case management and retrospective medical
bill review services, that are designed to reduce costs associated with
work-related injuries and automobile accident-related injuries. Revenues from
specialized cost containment services comprised approximately 33.8% of revenues
for 1996, up from approximately 27.1% for 1995. CRA markets its services to
workers' compensation insurers, third-party administrators ("TPAs"),
self-insured employers and payors of automobile accident medical claims through
a direct sales and marketing organization consisting of over 150 dedicated
personnel. CRA currently has over 1,250 customers nationwide. CRA's executive
offices are located at 312 Union Wharf, Boston, Massachusetts 02109 and its
telephone number is (617) 367-2163. See "BUSINESS OF CRA."
 
    CONCENTRA.  Concentra, a Delaware corporation, was formed by OccuSystems and
CRA to consummate the Mergers and has not conducted any substantial business
activities to date. As a result of the Mergers, OccuSystems will be merged into
Concentra and CRA will become a wholly-owned subsidiary of Concentra.
Accordingly, the business of Concentra will be the business currently conducted
by OccuSystems and CRA. The mailing address of Concentra's principal executive
office is 312 Union Wharf, Boston, Massachusetts 02109 and its telephone number
is (617) 367-2163. See "BUSINESS OF CONCENTRA."
 
THE SPECIAL MEETINGS
 
    OCCUSYSTEMS.  The OccuSystems Meeting will be held at the Holiday Inn, 4441
Highway 114 and Esters Boulevard, Irving, Texas 75063 on       , 1997, starting
at 10:00 a.m., local time. See "THE SPECIAL MEETINGS." At the OccuSystems
Meeting, holders of OccuSystems Common Stock will be asked to approve and adopt
the OccuSystems Proposal, the Concentra Incentive Plan and the Concentra
 
                                       5
<PAGE>
Employee Stock Purchase Plan. The Reorganization Agreement, the Concentra
Incentive Plan and the Concentra Employee Stock Purchase Plan are included
herewith as Appendices A, G and H, respectively. See "THE MERGERS," "THE
REORGANIZATION AGREEMENT," "DESCRIPTION OF THE CONCENTRA 1997 LONG-TERM
INCENTIVE PLAN," and "DESCRIPTION OF THE CONCENTRA EMPLOYEE STOCK PURCHASE
PLAN."
 
    Holders of record of OccuSystems Common Stock at the close of business on
      , 1997 (the "OccuSystems Record Date") have the right to receive notice of
and to vote at the OccuSystems Meeting. On       , 1997, there were       shares
of OccuSystems Common Stock outstanding and entitled to vote. Each share of
OccuSystems Common Stock is entitled to one vote on each matter that is properly
presented to stockholders for a vote at the OccuSystems Meeting. Under the
Delaware General Corporation Law (the "DGCL"), the affirmative vote of the
holders of a majority of the outstanding shares of OccuSystems Common Stock is
required to approve and adopt the OccuSystems Proposal. The affirmative vote of
the holders of a majority of total combined shares present and eligible to vote
at the OccuSystems Meeting and the CRA Meeting (after giving effect to the
Exchange Ratio to be applied in the Mergers) is required to approve the
Concentra Incentive Plan and the Concentra Employee Stock Purchase Plan.
 
    As of April 30, 1997, directors and executive officers of OccuSystems as a
group beneficially owned 870,687 shares of OccuSystems Common Stock, or
approximately 4.0% of those shares outstanding as of such date and, including
shares issuable upon exercise of options that will vest at the Effective Time as
a result of the Mergers, such persons beneficially owned 1,257,762 shares or
approximately 5.8% of those shares outstanding as of such date.
 
    CRA.  The CRA Meeting will be held at the offices of Hutchins, Wheeler &
Dittmar, 101 Federal Street, Boston, Massachusetts 02110, on       , 1997,
starting at 10:00 a.m., local time. See "THE SPECIAL MEETINGS." At the CRA
Meeting, holders of CRA Common Stock will be asked to approve and adopt the CRA
Proposal, the Concentra Incentive Plan and the Concentra Employee Stock Purchase
Plan. The Reorganization Agreement, the Concentra Incentive Plan and the
Concentra Employee Stock Purchase Plan are included herewith as Appendices A, G
and H, respectively. See "THE MERGERS," "THE REORGANIZATION AGREEMENT,"
"DESCRIPTION OF THE CONCENTRA 1997 LONG-TERM INCENTIVE PLAN" and "DESCRIPTION OF
THE CONCENTRA EMPLOYEE STOCK PURCHASE PLAN."
 
    Holders of record of CRA Common Stock at the close of business on       ,
1997 (the "CRA Record Date") have the right to receive notice of and to vote at
the CRA Meeting. On       , 1997, there were       shares of CRA Common Stock
outstanding and entitled to vote. Each share of CRA Common Stock is entitled to
one vote on each matter that is properly presented to stockholders for a vote at
the CRA Meeting. Under the Massachusetts Business Corporation Law (the "MBCL"),
the affirmative vote of the holders of two-thirds of the outstanding shares of
CRA Common Stock is required to approve and adopt the CRA Proposal. The
affirmative vote of the holders of a majority of total combined shares present
and eligible to vote at the CRA Meeting and the OccuSystems Meeting (after
giving effect to the Exchange Ratio to be applied in the Mergers) is required to
approve the Concentra Incentive Plan and the Concentra Employee Stock Purchase
Plan.
 
    As of April 30, 1997, directors and executive officers of CRA as a group
beneficially owned 1,447,347 shares of CRA Common Stock, or approximately 16.1%
of those shares outstanding as of such date.
 
THE REORGANIZATION AGREEMENT
 
    GENERAL.  The Reorganization Agreement provides, among other things, for the
merger of OccuSystems into Concentra, with Concentra being the surviving
corporation in the OccuSystems Merger, and the merger of a wholly-owned
subsidiary of Concentra with and into CRA, with CRA being the surviving
corporation in the CRA Merger and becoming a wholly-owned subsidiary of
Concentra.
 
                                       6
<PAGE>
    CONVERSION OF OCCUSYSTEMS COMMON STOCK.  Upon consummation of the
OccuSystems Merger, each outstanding share of OccuSystems Common Stock will be
converted into one share of Concentra Common Stock (the "OccuSystems Ratio").
Each share of OccuSystems Common Stock which is held in the treasury of
OccuSystems ("OccuSystems Treasury Stock") will be canceled and cease to exist.
See "THE REORGANIZATION AGREEMENT -- Conversion of OccuSystems Common Stock."
For a description of the Concentra Common Stock, see "DESCRIPTION OF CONCENTRA
CAPITAL STOCK." For a summary of the principal differences between the rights of
holders of Concentra Common Stock and OccuSystems Common Stock, see "COMPARISON
OF STOCKHOLDERS' RIGHTS -- Comparison of Stockholders' Rights with Respect to
Concentra and OccuSystems."
 
    CONVERSION OF CRA COMMON STOCK.  Upon consummation of the CRA Merger, each
outstanding share of CRA Common Stock, other than shares held by holders who
have perfected appraisal rights ("Dissenting Shares"), will be converted into
the right to receive 1.786 shares of Concentra Common Stock (the "CRA Ratio").
See "THE REORGANIZATION AGREEMENT -- Conversion of CRA Common Stock." For a
description of the Concentra Common Stock, see "DESCRIPTION OF CONCENTRA COMMON
STOCK." For a summary of the principal differences between the rights of holders
of Concentra Common Stock and CRA Common Stock, see "COMPARISON OF STOCKHOLDERS'
RIGHTS -- Comparison of Stockholders' Rights with Respect to Concentra and CRA."
 
    FRACTIONAL SHARES.  No fractional shares of Concentra Common Stock will be
issued to any stockholder of OccuSystems or CRA upon consummation of the
Mergers. For each fractional share that would otherwise be issued, Concentra
will pay by check an amount equal to a pro rata portion of the net proceeds of
the sale by                (the "Exchange Agent") of shares of Concentra Common
Stock, representing the aggregate of all such fractional shares and the
aggregate dividends or other distributions that are payable with respect to such
shares of Concentra Common Stock. Such sales will be executed by the Exchange
Agent as soon as practicable after the effective time of the Mergers (the
"Effective Time") at then prevailing prices on the Nasdaq National Market.
 
    CONDITIONS TO THE MERGERS.  The obligations of OccuSystems and CRA to
consummate the Mergers are subject to the fulfillment of various conditions,
including, among others, (i) approval of the OccuSystems Proposal and the CRA
Proposal by the stockholders of OccuSystems and CRA, respectively, (ii)
expiration or termination of the applicable waiting period under the
Hart-Scott-Rodino Antitrust Improvements Act of 1976, as amended (the "HSR
Act"), (iii) the absence of any injunction or other order preventing or making
the Mergers illegal, (iv) the effectiveness of the Registration Statement and
the absence of any stop order suspending the effectiveness thereof and no
proceeding for that purpose having been initiated by the Commission, (v) receipt
of all required consents, authorizations, orders and approvals of (or filings or
registrations with) any governmental commission, board or other regulatory body
and (vi) approval of quotation of the Concentra Common Stock on the Nasdaq
National Market, subject only to official notice of issuance. See "THE
REORGANIZATION AGREEMENT -- Conditions to the Mergers."
 
    The obligation of OccuSystems to consummate the OccuSystems Merger is
subject to the satisfaction of certain additional conditions, including (i) the
performance by CRA of its obligations under the Reorganization Agreement and the
continued accuracy of the representations and warranties of CRA at the Closing
Date (as hereinafter defined) (subject to certain materiality exceptions), (ii)
the receipt by OccuSystems and Concentra of a satisfactory opinion of its
special counsel that the OccuSystems Merger will be treated as a reorganization
within the meaning of Section 368(a) of the Internal Revenue Code of 1986, as
amended (the "Code"), and that OccuSystems will not recognize any gain or loss
in the OccuSystems Merger, (iii) no material adverse change in the financial
condition, business or operations of CRA, (iv) holders of not more than five
percent of CRA Common Stock having perfected appraisal rights, (v) receipt of an
opinion dated as of the Closing Date from OccuSystems' auditors that the Mergers
would be properly accounted for as a pooling-of-interests and (vi) that the
fairness opinion of OccuSystems'
 
                                       7
<PAGE>
financial advisor shall not have been withdrawn or materially modified by such
financial advisor in a manner adverse to OccuSystems' stockholders.
 
    The obligation of CRA to consummate the CRA Merger is subject to the
satisfaction of certain additional conditions, including (i) the performance by
OccuSystems of its obligations under the Reorganization Agreement and the
continued accuracy of the representations and warranties of OccuSystems at the
Closing Date (subject to certain materiality exceptions), (ii) the receipt by
CRA of a satisfactory opinion of its special counsel that the CRA Merger will be
treated as a reorganization within the meaning of Section 368(a) of the Code
and/or the transfer of property governed by Section 351 of the Code, (iii) the
receipt by OccuSystems and Concentra of the tax opinion described in the
preceding paragraph, (iv) no material adverse change in the financial condition,
business or operations of OccuSystems, (v) receipt of an opinion dated as of the
Closing Date from CRA's auditors that the Mergers would be properly accounted
for as a pooling-of-interests and (vi) that the fairness opinion of CRA's
financial advisor shall not have been withdrawn or materially modified by such
financial advisor in a manner adverse to CRA's stockholders.
 
    TERMINATION OF THE REORGANIZATION AGREEMENT.  The Reorganization Agreement
is subject to termination at the option of either OccuSystems or CRA if the
Mergers are not consummated on or before October 31, 1997; prior to such time,
by the mutual consent of OccuSystems and CRA; or upon the occurrence of certain
events. The Reorganization Agreement may be terminated by CRA, at any time prior
to the Effective Time, if (i) in the exercise of its fiduciary duties to its
stockholders, the CRA Board determines that such termination is required by
reason of a CRA Alternative Proposal (as hereinafter defined) being made, (ii)
there has been a breach by OccuSystems of any representation or warranty in the
Reorganization Agreement which would have, or which would be reasonably likely
to have, a material adverse effect on OccuSystems, (iii) there has been a
material breach by OccuSystems of any of its covenants or agreements in the
Reorganization Agreement which is not curable or, if curable, is not cured
within 30 days after written notice of the breach, or (iv) the OccuSystems Board
shall have withdrawn or modified, in a manner materially adverse to CRA, its
approval or recommendation of the Reorganization Agreement or the Mergers.
OccuSystems may terminate the Reorganization Agreement, at any time prior to the
Effective Time, if (i) in the exercise of its fiduciary duties to its
stockholders, the OccuSystems Board determines that such termination is required
by reason of an OccuSystems Alternative Proposal (as hereinafter defined) being
made, (ii) there has been a breach by CRA of any representation or warranty in
the Reorganization Agreement which would have, or which would be reasonably
likely to have, a material adverse effect on CRA, (iii) there has been a
material breach by CRA of any of its covenants or agreements in the
Reorganization Agreement which is not curable or not cured within 30 days of
written notice of the breach, or (iv) the CRA Board shall have withdrawn or
modified in a manner materially adverse to OccuSystems its approval or
recommendation of the Reorganization Agreement or the Mergers. See "THE
REORGANIZATION AGREEMENT -- Termination of the Reorganization Agreement."
 
    TERMINATION FEES.  If a CRA Alternative Proposal is made and thereafter the
Reorganization Agreement is terminated (i) by action of the CRA Board in the
exercise of its fiduciary duties by reason of such CRA Alternative Proposal or
(ii) by action of OccuSystems if the CRA Board has withdrawn or modified in a
manner materially adverse to OccuSystems its approval or recommendation of the
Reorganization Agreement or the Mergers, then CRA must pay OccuSystems a
termination fee of $10 million. If an OccuSystems Alternative Proposal is made
and thereafter the Reorganization Agreement is terminated (i) by action of the
OccuSystems Board in the exercise of its fiduciary duties by reason of such
OccuSystems Alternative Proposal or (ii) by action of the CRA Board if the
OccuSystems Board has withdrawn or modified in a manner materially adverse to
CRA its approval or recommendation of the Reorganization Agreement or the
Mergers, then OccuSystems must pay CRA a termination fee of $10 million. See
"THE REORGANIZATION AGREEMENT -- Termination Fees."
 
                                       8
<PAGE>
THE STOCK OPTION AGREEMENTS
 
    Pursuant to (i) the OccuSystems, Inc. Stock Option Agreement dated as of
April 21, 1997 (the "OccuSystems Stock Option Agreement"), by and between
OccuSystems and CRA, and (ii) the CRA Managed Care, Inc. Stock Option Agreement
dated as of April 21, 1997 (the "CRA Stock Option Agreement" and, together with
the OccuSystems Stock Option Agreement, the "Stock Option Agreements"), by and
between CRA and OccuSystems, OccuSystems has granted to CRA the right (the "CRA
Option"), and CRA has granted to OccuSystems the right (the "OccuSystems Option"
and, together with the CRA Option, the "Options"), to purchase, upon the
occurrence of an event that requires the corporation issuing the option (the
"Issuer") to pay a termination fee as described in the previous paragraph, up to
ten percent of the authorized and outstanding shares of the common stock of the
Issuer as of March 31, 1997, at a price of $21.21 per share for OccuSystems
Common Stock and $37.875 per share for CRA Common Stock. In addition, the Stock
Option Agreements provide that the holder of an Option has the right to require
the Issuer to repurchase from the holder of the Option at any time the Option is
exercisable (i) all or any portion of the Option at a price equal to the
difference between the Market Price (as hereinafter defined) and the exercise
price of the Option, and (ii) any shares purchased pursuant to the Option. The
Stock Options also provide that neither OccuSystems' nor CRA's Total Profit (as
hereinafter defined) from the Option Agreements and the termination fees
discussed above shall exceed $15 million. Further, the Stock Option Agreements
contain certain standstill provisions and provide that any shares acquired must
be voted for and against each matter subject to stockholder vote in the same
proportion as the other stockholders of the Issuer voted for and against such
matter. See "THE STOCK OPTION AGREEMENTS -- Standstill Provisions" and "THE
STOCK OPTION AGREEMENTS." Copies of the Stock Option Agreements are attached
hereto as Appendices B and C.
 
THE MERGERS
 
    OWNERSHIP OF CONCENTRA AFTER THE MERGERS.  Immediately following the
Mergers, assuming that no CRA stockholders exercise dissenters rights of
appraisal under the MBCL, (i) the former holders of OccuSystems Common Stock
will collectively hold approximately 57.3% of the issued and outstanding shares
of Concentra Common Stock and (ii) the former holders of CRA Common Stock will
collectively hold approximately 42.7% of the issued and outstanding shares of
Concentra Common Stock.
 
    RECOMMENDATION OF OCCUSYSTEMS BOARD; OCCUSYSTEMS' REASONS FOR THE
MERGERS.  The OccuSystems Board, by unanimous vote, has determined that the
Mergers are in the best interests of the holders of OccuSystems Common Stock and
recommends that holders of OccuSystems Common Stock vote in favor of the
OccuSystems Proposal. The decision of the OccuSystems Board to enter into the
Reorganization Agreement and to recommend that stockholders vote in favor of the
OccuSystems Proposal is based upon its evaluation of a number of factors. See
"THE MERGERS -- Recommendation of OccuSystems Board; OccuSystems' Reasons for
the Mergers" and "-- Opinions of Financial Advisors -- Opinion of OccuSystems'
Financial Advisors."
 
    RECOMMENDATION OF CRA BOARD; CRA'S REASONS FOR THE MERGERS.  The CRA Board,
by unanimous vote, has determined that the Mergers are in the best interests of
the holders of CRA Common Stock and recommends that holders of CRA Common Stock
vote in favor of the CRA Proposal. The decision of the CRA Board to enter into
the Reorganization Agreement and to recommend that stockholders vote in favor of
the CRA Proposal is based on its evaluation of a number of factors. See "THE
MERGERS -- Recommendation of CRA Board; CRA's Reasons for the Mergers and "--
Opinions of Financial Advisors -- Opinion of CRA's Financial Advisor."
 
    INTEREST OF CERTAIN PERSONS IN THE MERGERS; MANAGEMENT OF CONCENTRA AFTER
THE MERGERS.  Certain members of the management of OccuSystems and CRA and the
OccuSystems Board and the CRA Board have certain interests in the Mergers that
are different from, or in addition to, the interests of stockholders of
OccuSystems and CRA generally. Pursuant to the Reorganization Agreement,
OccuSystems and CRA
 
                                       9
<PAGE>
will designate the directors and officers of Concentra. It is anticipated that
John K. Carlyle, Robert W. O'Leary, Robert A. Ortenzio and Paul B. Queally,
currently directors of OccuSystems, and Donald J. Larson, Lois E. Silverman,
George H. Conrades and Mitchell T. Rabkin, M.D., currently directors of CRA,
will become directors of Concentra. These directors will all be Continuing
Directors for purposes of the Indenture (as hereinafter defined) relating to
OccuSystems' outstanding convertible notes (the "OccuSystems Notes"). Certain
executive officers of OccuSystems and CRA will become executive officers of
Concentra. See "THE MERGERS -- Interests of Certain Persons in the Mergers."
 
    REGULATORY APPROVALS.  The Mergers are subject to the requirements of the
HSR Act and the rules and regulations thereunder, which provide that certain
transactions may not be consummated until required information and materials are
furnished to the Antitrust Division of the Department of Justice (the "Antitrust
Division") and the Federal Trade Commission (the "FTC") and the requisite
waiting period has expired or is terminated. OccuSystems and CRA filed the
required information and materials with the Antitrust Division and the FTC
effective May 13, 1997. See "THE MERGERS -- Regulatory Approvals."
 
    ACCOUNTING TREATMENT.  OccuSystems and CRA have received a "pooling letter"
from Arthur Andersen LLP, their independent public accountants, dated April 21,
1997, to the effect that the Mergers will be treated as a pooling of interests
for accounting purposes. See "THE MERGERS -- Accounting Treatment" and "THE
REORGANIZATION AGREEMENT -- Conditions to the Mergers."
 
    OPINIONS OF FINANCIAL ADVISORS. OCCUSYSTEMS.  On April 16, 1997, Donaldson,
Lufkin & Jenrette Securities Corporation ("DLJ") made a presentation to the
OccuSystems Board (subsequently confirmed in writing in an opinion dated April
21, 1997) to the effect that, as of the date of such opinion, and based on and
subject to, the assumptions, limitations and qualifications set forth in such
opinions, the quotient of the OccuSystems Ratio and the CRA Ratio (the "Exchange
Ratio") is fair to the holders of OccuSystems Common Stock from a financial
point of view. The full text of the written opinion of DLJ, dated April 21,
1997, which sets forth assumptions made, factors considered and limitations on
the review undertaken by DLJ, is included as Appendix D to this Joint Proxy
Statement/Prospectus. OccuSystems stockholders are urged to read such opinion
carefully in its entirety. The opinion of DLJ is directed to the OccuSystems
Board, addresses only the Exchange Ratio from a financial point of view, and
does not constitute a recommendation to any stockholder as to how such
stockholder should vote at the OccuSystems Meeting. See "THE MERGERS -- Opinions
of Financial Advisors -- Opinion of OccuSystems' Financial Advisor."
 
    CRA.  On April 21, 1997, Alex. Brown & Sons Incorporated ("Alex. Brown"),
financial advisor to CRA, rendered to the CRA Board an opinion to the effect
that, as of such date and based upon and subject to certain matters stated in
such opinion, the Exchange Ratio was fair to the holders of CRA Common Stock
from a financial point of view. The full text of the written opinion of Alex.
Brown dated as of April 21, 1997, which sets forth assumptions made, factors
considered and limitations on the review undertaken by Alex. Brown, is included
as Appendix E to this Joint Proxy Statement/Prospectus and should be read
carefully in its entirety. The opinion of Alex. Brown is directed to the CRA
Board of Directors, addresses only the fairness of the Exchange Ratio from a
financial point of view, and does not constitute a recommendation to any
stockholder as to how such stockholder should vote at the CRA Meeting. See "THE
MERGERS -- Opinions of Financial Advisors -- Opinion of CRA's Financial
Advisor."
 
    CERTAIN FEDERAL INCOME TAX CONSEQUENCES.  It is a condition to OccuSystems'
and CRA's obligations to consummate the Mergers that OccuSystems and Concentra
receive an opinion from Vinson & Elkins L.L.P., special counsel to OccuSystems
and Concentra, based upon reasonably requested representation letters, that the
OccuSystems Merger will be treated as a reorganization described in Section
368(a) of the Code and that OccuSystems will not recognize any gain or loss in
the OccuSystems Merger. It is a condition to CRA's obligation to consummate the
CRA Merger that CRA receive an opinion from Hutchins, Wheeler & Dittmar, a
Professional Corporation, special counsel to CRA, based upon reasonably
requested representation letters, that the CRA Merger will be treated as a
reorganization described in
 
                                       10
<PAGE>
Section 368(a) of the Code and/or a transfer of property under Section 351 of
the Code. No gain or loss generally will be recognized by a holder of CRA Common
Stock who exchanges such stock solely for Concentra Common Stock pursuant to the
CRA Merger. Holders of CRA Common Stock may recognize gain or loss by reason of
cash received in lieu of fractional shares or by reason of exercising
dissenters' rights of appraisal. See "THE MERGERS -- Certain Federal Income Tax
Consequences."
 
    DISSENTERS' RIGHTS.  Holders of OccuSystems Common Stock are not entitled to
dissenters' or appraisal rights in connection with the OccuSystems Merger.
Holders of CRA Common Stock (i) who file with CRA before the taking of the vote
of the stockholders on the CRA Proposal, written objection to the proposed
action stating that such holder intends to demand payment for such holder's
shares if the action is taken and (ii) whose shares are not voted in favor of
the proposed action, and who have otherwise properly complied with Section 86 of
the MBCL, will be entitled to dissenters' rights. See "THE MERGERS --
Dissenters' Rights."
 
                                       11
<PAGE>
                        SUMMARY HISTORICAL AND PRO FORMA
                             FINANCIAL INFORMATION
 
OCCUSYSTEMS HISTORICAL CONSOLIDATED FINANCIAL INFORMATION
 
    The following table sets forth summary historical consolidated financial
information of OccuSystems and has been derived from and should be read in
conjunction with OccuSystems' audited consolidated financial statements and
unaudited interim consolidated financial statements, including the notes
thereto, which are incorporated by reference in this Joint Proxy
Statement/Prospectus. Unaudited interim data reflects, in the opinion of
OccuSystems' management, all adjustments (consisting only of normal recurring
adjustments) considered necessary for a fair presentation of results for such
interim periods. Results of operations for unaudited interim periods are not
necessarily indicative of results which may be expected for any other interim or
annual period.
<TABLE>
<CAPTION>
                                                                                                         THREE MONTHS ENDED
                                                              YEAR ENDED DECEMBER 31,                        MARCH 31,
                                              --------------------------------------------------------  --------------------
<S>                                           <C>        <C>         <C>        <C>         <C>         <C>        <C>
                                                1992      1993(1)      1994        1995        1996       1996       1997
                                              ---------  ----------  ---------  ----------  ----------  ---------  ---------
 
<CAPTION>
                                                                  (IN THOUSANDS, EXCEPT PER SHARE DATA)
<S>                                           <C>        <C>         <C>        <C>         <C>         <C>        <C>
STATEMENT OF OPERATIONS DATA:
  Net revenues..............................  $  14,937  $   64,185  $  85,502  $  136,986  $  170,035  $  38,331  $  46,383
  Operating income (loss) from continuing
    operations..............................        452     (17,910)     1,768      10,322      19,742      2,734      5,735
  Interest expense..........................        489       1,710      1,869       3,015       2,064        560      1,598
  Income (loss) from continuing operations
    before extraordinary charge.............        (76)    (19,538)    (1,149)      3,900      11,033      1,275      3,013
  Net income (loss).........................  $     156  $  (19,386) $    (773) $    3,220  $   11,033  $   1,275  $   3,013
  Income (loss) per share from continuing
    operations before extraordinary
    charge..................................  $   (0.01) $    (1.58) $   (0.08) $     0.22  $     0.51  $    0.07  $    0.14
  Net income (loss) per share...............  $    0.03  $    (1.57) $   (0.05) $     0.19  $     0.51  $    0.07  $    0.14
  Weighted average number of common shares
    outstanding.............................      5,317      12,358     14,333      19,115      22,029     21,662     22,316
  Basic earnings per share from continuing
    operations(2)...........................                         $   (0.08) $     0.22  $     0.50  $    0.07  $    0.14
  Basic weighted average shares
    outstanding(2)..........................                             9,616      17,474      20,766     19,451     21,575
</TABLE>
 
<TABLE>
<CAPTION>
                                                                         AS OF DECEMBER 31,                       AS OF
                                                       -------------------------------------------------------  MARCH 31,
                                                         1992       1993       1994        1995        1996        1997
                                                       ---------  ---------  ---------  ----------  ----------  ----------
<S>                                                    <C>        <C>        <C>        <C>         <C>         <C>
                                                                                 (IN THOUSANDS)
BALANCE SHEET DATA:
  Working capital....................................  $   1,131  $   8,551  $  11,573  $   12,244  $   96,271  $   86,045
  Total assets.......................................     39,926     51,937     76,650     146,369     260,619     263,628
  Long-term debt, net of current maturities..........     11,855     15,825     20,072      18,108      99,089      98,307
  Convertible exchangeable preferred stock(3)........     --         --         15,000      --          --          --
  Stockholders' equity...............................     18,764     19,949     20,039      94,586     132,541     136,119
</TABLE>
 
- ------------------------
(1) Operating results for the year ended December 31, 1993, include certain
    nonrecurring charges of approximately $20.6 million, principally incurred in
    connection with the write-down of goodwill.
 
(2) The Financial Accounting Standards Board has issued Statement of Accounting
    Standards No. 128 ("SFAS 128"), Earnings Per Share. SFAS 128 establishes new
    accounting standards for the presentation of earnings per share for periods
    ending after December 15, 1997 whereby primary earnings per share is
    replaced with "Basic Earnings Per Share." Under SFAS 128, Basic Earnings Per
    Share is computed by dividing reported earnings available to common
    stockholders by weighted average shares outstanding.
 
(3) The convertible exchangeable preferred stock was exchanged for a convertible
    debenture upon consummation of OccuSystems' initial public offering in May
    1995 and was subsequently converted into OccuSystems Common Stock in March
    1996.
 
                                       12
<PAGE>
CRA HISTORICAL CONSOLIDATED FINANCIAL INFORMATION
 
    The following table sets forth summary historical consolidated financial
information of CRA and has been derived from and should be read in conjunction
with CRA's audited consolidated financial statements and unaudited interim
consolidated financial statements, including the notes thereto, which are
incorporated by reference in this Joint Proxy Statement/Prospectus. Unaudited
interim data reflects, in the opinion of CRA's management, all adjustments
(consisting only of normal recurring adjustments) considered necessary for a
fair presentation of results for such interim periods. Results of operations for
unaudited interim periods are not necessarily indicative of results which may be
expected for any other interim or annual period.
<TABLE>
<CAPTION>
                                                                                                        THREE MONTHS ENDED
                                                             YEAR ENDED DECEMBER 31,                        MARCH 31,
                                            ---------------------------------------------------------  --------------------
<S>                                         <C>        <C>         <C>         <C>         <C>         <C>        <C>
                                              1992        1993        1994        1995        1996       1996       1997
                                            ---------  ----------  ----------  ----------  ----------  ---------  ---------
 
<CAPTION>
                                                                 (IN THOUSANDS, EXCEPT PER SHARE DATA)
<S>                                         <C>        <C>         <C>         <C>         <C>         <C>        <C>
STATEMENT OF OPERATIONS DATA:
  Revenues................................  $  80,851  $  100,546  $  121,295  $  146,055  $  179,652  $  40,225  $  54,489
  Operating income(1).....................      4,990       4,533       8,746      12,419      17,466      3,694      5,667
  Interest expense........................         66          16       4,087       2,484         770        194        166
  Income before taxes(1)..................      4,984       4,533       4,589       9,935      17,267      3,500      5,527
  Provision for income taxes(2)...........        307         355       5,302       3,974       7,166      1,453      2,432
  Net income (loss) before extraordinary
    items(1)(2)...........................  $   4,677  $    4,178  $     (713) $    5,961  $   10,101  $   2,047  $   3,095
  Pro forma(3) and actual earnings per
    share.................................                         $     0.57  $     0.91  $     1.19  $    0.27  $    0.34
  Weighted average shares outstanding.....                              4,815       6,540       8,475      7,550      9,102
  Basic earnings per share before
    extraordinary items(3)(4).............                         $     0.59  $     0.93  $     1.22  $    0.28  $    0.35
  Basic weighted average shares
    outstanding(4)........................                              4,700       6,431       8,284      7,373      8,935
</TABLE>
 
<TABLE>
<CAPTION>
                                                                           AS OF DECEMBER 31,                      AS OF
                                                         ------------------------------------------------------  MARCH 31,
                                                           1992       1993        1994       1995       1996        1997
                                                         ---------  ---------  ----------  ---------  ---------  ----------
<S>                                                      <C>        <C>        <C>         <C>        <C>        <C>
                                                                                   (IN THOUSANDS)
BALANCE SHEET DATA:
  Working capital......................................  $   9,114  $  12,126  $    5,609  $   7,493  $  19,345  $   23,359
  Total assets.........................................     15,894     20,836      31,345     36,556     98,128     102,378
  Long-term debt, net of current maturities............     --         --          37,500     --         --          --
  Stockholders' equity (deficit).......................     11,846     15,856     (28,513)    11,660     76,578      80,787
</TABLE>
 
- ------------------------
 
(1) Expenses for the period prior to the recapitalization of CRA in March 1994
    (the "Recapitalization") include certain compensation and other expenses,
    the levels of which are not comparable to the levels of such expenses for
    1994. Expenses for 1994 include increased investments in management
    information systems, personnel and certain other items.
 
(2) Prior to the Recapitalization, CRA elected to be taxed as an "S"
    Corporation. In connection with the Recapitalization, CRA was required to
    change from an "S" corporation. This change resulted in CRA recording an
    incremental tax provision of $3,772,000 in the first quarter of 1994.
 
(3) The pro forma net income of $2,753,000 and earnings per share for 1994 have
    been computed as if CRA had been subject to federal and state income taxes
    during the entire period based upon an effective tax rate indicative of the
    statutory rate in effect during the period.
 
                                         (FOOTNOTES CONTINUED ON FOLLOWING PAGE)
 
                                       13
<PAGE>
(4) The Financial Accounting Standards Board has issued Statement of Accounting
    Standards No. 128 ("SFAS 128"), Earnings Per Share. SFAS 128 establishes new
    accounting standards for the presentation of earnings per share for periods
    ending after December 15, 1997 whereby primary earnings per share is
    replaced with "Basic Earnings Per Share." Under SFAS 128, Basic Earnings Per
    Share is computed by dividing reported earnings available to common
    stockholders by weighted average shares outstanding.
 
CONSOLIDATED PRO FORMA FINANCIAL INFORMATION
 
    The following unaudited pro forma selected combined financial information
presents the consolidated financial data of OccuSystems and CRA for the years
ended December 31, 1994, 1995 and 1996 and as of and for the three months ended
March 31, 1997. The unaudited pro forma consolidated Statement of Operations
data give effect to the Mergers as if they had occurred on January 1, 1994 and
the unaudited pro forma consolidated balance sheet data give effect to the
Mergers as if they had occurred on March 31, 1997. Concentra will account for
the Mergers as a pooling-of-interests. The unaudited pro forma selected
consolidated condensed financial data have been derived from the unaudited pro
forma combined condensed financial statements starting at page 58 and should be
read in conjunction with those statements, the related notes thereto and the
separate historical financial statements of OccuSystems and CRA incorporated
herein by reference. See "INCORPORATION OF CERTAIN DOCUMENTS BY REFERENCE." The
pro forma data are not necessarily indicative of the actual or future results of
operations or financial condition that would have been reported had the Mergers
occurred on the dates assumed. The unaudited pro forma selected combined
financial information does not reflect certain deal fees and transition costs
expected to result from the Mergers. See "PRO FORMA FINANCIAL INFORMATION."
 
<TABLE>
<CAPTION>
                                                                                              THREE MONTHS ENDED
                                                               YEARS ENDED DECEMBER 31,            MARCH 31,
                                                          ----------------------------------  -------------------
                                                             1994        1995        1996            1997
                                                          ----------  ----------  ----------  -------------------
<S>                                                       <C>         <C>         <C>         <C>
                                                                   (IN THOUSANDS, EXCEPT PER SHARE DATA)
STATEMENT OF OPERATIONS DATA:
  Revenue...............................................  $  206,797  $  283,041  $  349,687      $   100,872
  Operating income......................................      10,514      22,741      37,208           11,402
  Income before taxes...................................       4,666      17,494      34,400           10,162
  Provision for income taxes............................       3,062       7,633      13,266            4,054
  Net income(1).........................................  $    1,604  $    9,861  $   21,134      $     6,108
  Earnings per share....................................  $     0.07  $     0.33  $     0.57      $      0.16
  Weighted average shares outstanding(2)................      22,933      30,795      37,165           38,572
  Basic earnings per share(3)...........................  $     0.11  $     0.41  $     0.73      $      0.20
  Basic weighted average shares outstanding(3)..........      14,316      23,905      29,050           30,510
</TABLE>
 
<TABLE>
<CAPTION>
                                                                                                      AS OF
                                                                                                 MARCH 31, 1997
                                                                                               -------------------
<S>                                                                                            <C>
BALANCE SHEET:
  Working capital............................................................................      $   109,404
  Total assets...............................................................................          366,006
  Long-term debt, net of current maturities..................................................           98,307
  Stockholders' equity.......................................................................          216,906
</TABLE>
 
- ------------------------
 
(1) The net income amounts presented are before any extraordinary items and
    discontinued operations.
 
(2) The weighted average shares outstanding has been adjusted to reflect the
    issuance of shares in accordance with the exchange ratio stated in the
    Reorganization Agreement, whereby each share of CRA Common Stock will be
    exchanged for 1.786 shares of Concentra Common Stock and each share of
    OccuSystems Common Stock will be exchanged for one share of Concentra Common
    Stock.
 
(3) The Financial Accounting Standards Board has issued Statement of Accounting
    Standards No. 128 ("SFAS 128"), Earnings Per Share. SFAS 128 establishes new
    accounting standards for the presentation of earnings per share for periods
    ending after December 15, 1997 whereby primary earnings per share is
    replaced with "Basic Earnings Per Share." Under SFAS 128, Basic Earnings Per
    Share is computed by dividing reported earnings available to common
    stockholders by weighted average shares outstanding.
 
                                       14
<PAGE>
                           COMPARATIVE PER SHARE DATA
 
    The following table sets forth for the OccuSystems Common Stock and CRA
Common Stock selected historical per share data and the corresponding unaudited
pro forma per share amounts for the periods indicated, giving effect to the
Mergers. The data presented are based upon the consolidated financial statements
and related notes of each of OccuSystems and CRA incorporated herein by
reference and the unaudited pro forma combined balance sheet and income
statements, including the notes thereto, appearing elsewhere herein. This
information should be read in conjunction with, and is qualified in its entirety
by, the historical and unaudited pro forma combined financial statements and
related notes thereto. The assumptions used in the preparation of this table
appear under "PRO FORMA FINANCIAL INFORMATION." The comparative per share data
are not necessarily indicative of the results of the future operations of the
combined organization or the actual results that would have occurred if the
Mergers had been consummated at the beginning of the periods indicated.
 
<TABLE>
<CAPTION>
                                                                                              CRA
                                                             OCCUSYSTEMS       CRA         PRO FORMA        PRO FORMA
                                                             HISTORICAL    HISTORICAL    EQUIVALENT(1)    CONCENTRA(2)
                                                            -------------  -----------  ---------------  ---------------
<S>                                                         <C>            <C>          <C>              <C>
Book value per common share:
  December 31, 1996.......................................    $    6.21     $    8.58      $    4.80        $    5.62
  March 31, 1997..........................................         6.31          9.01           5.04             5.77
Earnings per share:
  Year ended December 31, 1994............................    $   (0.08)    $    0.57(3)    $    0.32       $    0.07
  Year ended December 31, 1995............................         0.22          0.91           0.51             0.33
  Year ended December 31, 1996............................         0.51          1.19           0.67             0.57
  Three months ended March 31, 1997.......................         0.14          0.34           0.19             0.16
</TABLE>
 
- ------------------------
 
(1) Represents the CRA historical amounts divided by the CRA Ratio (1.786).
 
(2) See "Unaudited Pro Forma Financial Information."
 
(3) The pro forma net income of $2,753,000 and earnings per share have been
    computed as if CRA had been subject to federal and state income taxes during
    the entire period based upon an effective tax rate indicative of the
    statutory rate in effect during the period.
 
COMPARATIVE MARKET PRICES AND DIVIDENDS
 
    OccuSystems Common Stock is listed on the Nasdaq National Market under the
symbol "OSYS." CRA Common Stock is listed on the Nasdaq National Market under
the symbol "CRAA."
 
    On April 21, 1997, the last full trading day preceding public announcement
of the proposed Mergers, the closing price per share of OccuSystems Common Stock
on the Nasdaq National Market was $19 1/8 and the closing price per share of CRA
Common Stock on the Nasdaq National Market was $37 7/8. On May 13, 1997, the
most recent practicable date prior to the printing of this Joint Proxy
Statement/Prospectus, the closing price per share of OccuSystems Common Stock on
the Nasdaq National Market was $22 3/4 and the closing price per share of CRA
Common Stock on the Nasdaq National Market was $39 5/8. See "COMPARATIVE PER
SHARE MARKET PRICE AND DIVIDEND INFORMATION."
 
    Holders of OccuSystems Common Stock and CRA Common Stock are urged to obtain
current market quotations prior to making any decision with respect to the
Mergers.
 
    Neither CRA nor OccuSystems has ever paid dividends. The payment of future
dividends on Concentra Common Stock will be a business decision to be made by
the Board of Directors of Concentra from time to time based upon results of
operations and financial condition of Concentra and such other factors as the
Concentra Board of Directors considers relevant.
 
                                       15
<PAGE>
QUOTATION OF CONCENTRA COMMON STOCK
 
    Concentra intends to apply for the quotation of Concentra Common Stock on
the Nasdaq National Market, and it is anticipated that such shares will be
quoted on the Nasdaq National Market upon official notice of issuance under the
symbol "CCMC." It is a condition to OccuSystems' and CRA's obligations to
consummate the Mergers that the shares of Concentra Common Stock to be issued to
OccuSystems' and CRA's stockholders in connection with the Mergers shall have
been approved for quotation on the Nasdaq National Market subject only to
official notice of issuance. See "THE MERGERS -- Quotation of Concentra Common
Stock."
 
                                       16
<PAGE>
                    RISK FACTORS AND CERTAIN CONSIDERATIONS
 
    Stockholders should carefully review the following factors together with the
other information contained and incorporated by reference in this Joint Proxy
Statement/Prospectus prior to voting on the proposals herein.
 
CAUTIONARY STATEMENT REGARDING FORWARD-LOOKING INFORMATION
 
    Words such as "believe," "anticipate," "expect," "plan," "intend,"
"estimate," "project," "will," "could," "may" and words of similar import are
intended to identify forward looking statements within the meaning of Section
27A of the Securities Act and Section 21E of the Exchange Act which are used in
this Joint Proxy Statement Prospectus and the documents incorporated by
reference herein. All statements other than statements of historical facts
included or incorporated by reference in this Joint Proxy Statement/Prospectus,
including, without limitation, statements regarding OccuSystems', CRA's or
Concentra's future financial results, financial position, business strategy,
budgets, projected costs and plans and objectives of management for future
operations, are forward looking statements. Although OccuSystems and CRA believe
their expectations reflected in such forward looking statements are based on
reasonable assumptions, no assurance can be given that such expectations will
prove to have been correct. Important factors that could cause actual results to
differ materially from the expectations reflected in the forward looking
statements herein include, among others, product and service demand and
acceptance, the availability of appropriate acquisition and joint venture
candidates, economic conditions, the impact of competition and pricing, changes
in the availability, cost and terms of financing, the impact of present or
future occupational, healthcare and insurance legislation and related
legislation or rule making, the continued availability and functionality of data
processing equipment and licensed software, the impact of possible litigation
and changes in operating expenses. For a more detailed discussion of the factors
which could cause actual results to vary from those disclosed in forward looking
statements, reference is made to the following factors and to the cautionary
language contained in each Company's periodic reports that are incorporated
herein by reference. All subsequent written or oral forward looking statements
attributable to CRA or OccuSystems, or persons acting on their behalf, are
expressly qualified in their entirety by the foregoing cautionary statements.
 
FIXED MERGER CONSIDERATION
 
    Stockholders of OccuSystems and CRA should consider that the merger
consideration is fixed. Holders of OccuSystems Common Stock will receive one
share of Concentra Common Stock for each share of OccuSystems Common Stock held.
Holders of CRA Common Stock will receive 1.786 shares of Concentra Common Stock
for each share of CRA Common Stock held. As a result, the merger consideration
will not be adjusted in the event of an increase or decrease in the market price
of OccuSystems Common Stock or CRA Common Stock. Stockholders of OccuSystems and
CRA are urged to obtain current stock market quotations for OccuSystems Common
Stock and CRA Common Stock. See "THE REORGANIZATION AGREEMENT."
 
UNCERTAINTIES RELATING TO COMBINATION OF BUSINESSES
 
    OccuSystems and CRA have entered into the Reorganization Agreement with the
expectation that the Mergers will benefit OccuSystems' and CRA's stockholders.
See "THE MERGERS -- Recommendation of OccuSystems Board; OccuSystems' Reasons
for the Mergers" and "-- Recommendation of CRA Board; CRA's Reasons for the
Mergers." There can be no assurance that OccuSystems and CRA will integrate
their businesses and management teams successfully or that Concentra will
achieve desired synergies or cost savings. The failure to integrate the two
companies' operations or management teams successfully or to achieve such
synergies or cost savings would have a material adverse effect on Concentra.
 
                                       17
<PAGE>
NO PRIOR PUBLIC MARKET; POSSIBLE VOLATILITY OF STOCK PRICE
 
    Prior to the Mergers, there will have been no public market for Concentra
Common Stock. Although OccuSystems Common Stock and CRA Common Stock have been
actively traded, there can be no assurance that an active trading market will
develop or be sustained for Concentra Common Stock. Following the Mergers, the
market price for Concentra Common Stock may be highly volatile depending on
various factors, including the general economy, stock market conditions,
announcements by Concentra and its competitors and fluctuations in Concentra's
overall operating results. In addition, the stock market historically has
experienced volatility which has affected the market price of securities of many
companies and which has sometimes been unrelated to the operating performance of
such companies. The trading price of Concentra Common Stock could also be
subject to significant fluctuations in response to variations in quarterly
results of operations, changes in earnings estimates by analysts, governmental
regulatory action, general trends in the industry, overall market conditions and
other factors. No assurance can be given or prediction made as to the
relationship between trading prices for OccuSystems Common Stock and CRA Common
Stock prior to the completion of the Mergers and future trading prices for
Concentra Common Stock following the Mergers.
 
PENDING ACCOUNTING DEVELOPMENTS
 
    The American Institute of Certified Public Accountants has proposed a change
to the accounting and reporting treatment of start-up costs. This proposal,
which is not yet final, would require that start-up costs be expensed as
incurred. At December 31, 1996, OccuSystems had approximately $1.6 million of
deferred start-up costs which would be required to be written off if the
proposed pronouncement is adopted.
 
MATERIAL BENEFITS TO INSIDERS
 
    Consummation of the Mergers will constitute a "change of control" under
certain options or rights to purchase shares of OccuSystems Common Stock (each
an "OccuSystems Option") held by OccuSystems' directors and executive officers.
As a result, OccuSystems Options to purchase an aggregate of 387,075 shares of
OccuSystems Common Stock that would not otherwise vest and become exercisable
until certain dates after the Effective Time will, by virtue of consummation of
the Mergers, vest and become exercisable as of the Effective Time. In addition,
certain officers of OccuSystems and CRA have entered into employment agreements
with Concentra which will become effective upon the Effective Time. Dr. Richard
D. Rehm, a director of OccuSystems, and Lois E. Silverman, Chairman of CRA, have
entered into agreements pursuant to which they will receive lump sum payments
upon termination of their employment with OccuSystems and CRA, respectively, at
the Effective Time. The terms of the Reorganization Agreement and consummation
of the Mergers may also provide the directors and officers of OccuSystems and
CRA with indemnification and other benefits. See "THE MERGERS -- Interests of
Certain Persons in the Merger" and "MANAGEMENT OF CONCENTRA -- Compensation of
Executive Officers."
 
                                       18
<PAGE>
                              THE SPECIAL MEETINGS
 
    This Joint Proxy Statement/Prospectus is furnished in connection with the
solicitation of proxies (i) from the holders of OccuSystems Common Stock by the
OccuSystems Board for use at the OccuSystems Meeting and (ii) from the holders
of CRA Common Stock by the CRA Board for use at the CRA Meeting.
 
TIMES AND PLACES; PURPOSES
 
    OCCUSYSTEMS.  The OccuSystems Meeting will be held at the Holiday Inn, 4441
Highway 114 at Esters Boulevard, Irving, Texas 75063, on       , 1997, starting
at 10:00 a.m., local time. At the OccuSystems Meeting, the stockholders of
OccuSystems will be asked to consider and vote upon the OccuSystems Proposal,
the Concentra Incentive Plan, the Concentra Employee Stock Purchase Plan and
such other matters as may properly come before the OccuSystems Meeting. The
Reorganization Agreement, the Concentra Incentive Plan and the Concentra
Employee Stock Purchase Plan are included herewith as Appendices A, G and H,
respectively.
 
    CRA.  The CRA Meeting will be held at the offices of Hutchins, Wheeler &
Dittmar, 101 Federal Street, Boston, Massachusetts 02110 on       , 1997,
starting at 10:00 a.m., local time. At the CRA Meeting, the stockholders of CRA
will be asked to consider and vote upon the CRA Proposal, the Concentra
Incentive Plan, the Concentra Employee Stock Purchase Plan and such other
matters as may properly come before the CRA Meeting. The Reorganization
Agreement, the Concentra Incentive Plan and the Concentra Employee Stock
Purchase Plan are included herewith as Appendices A, G and H, respectively. A
copy of the CRA Merger Agreement is attached as Appendix F to this Joint Proxy
Statement/Prospectus.
 
VOTING RIGHTS; VOTES REQUIRED FOR APPROVAL
 
    OCCUSYSTEMS.  The OccuSystems Board has fixed the close of business on
      , 1997, as the OccuSystems Record Date. Only holders of record of shares
of OccuSystems Common Stock on the OccuSystems Record Date are entitled to
notice of and to vote at the OccuSystems Meeting. As of       , 1997, there were
      shares of OccuSystems Common Stock outstanding and entitled to vote held
by approximately       stockholders of record.
 
    Each holder of record, as of the OccuSystems Record Date, of OccuSystems
Common Stock is entitled to cast one vote per share. The presence, in person or
by proxy, of the holders of a majority of the outstanding shares of OccuSystems
Common Stock entitled to vote is necessary to constitute a quorum at the
OccuSystems Meeting.
 
    Under the DGCL, the affirmative vote, in person or by proxy, of the holders
of a majority of the shares of OccuSystems Common Stock outstanding on the
OccuSystems Record Date is required to approve and adopt the OccuSystems
Proposal. The affirmative vote of the holders of a majority of total combined
shares present and eligible to vote at the OccuSystems Meeting and the CRA
Meeting (after giving effect to the Exchange Ratio to be applied in the Mergers)
is required to approve the Concentra Incentive Plan and the Concentra Employee
Stock Purchase Plan.
 
    As of April 30, 1997, directors and executive officers of OccuSystems as a
group beneficially owned 870,687 shares of OccuSystems Common Stock, or
approximately 4.0% of those shares of OccuSystems Common Stock outstanding as of
such date and, including shares issuable upon exercise of options that will vest
at the Effective Time as a result of the Mergers, such persons beneficially
owned 1,257,762 shares or approximately 5.8% of those shares outstanding as of
such date.
 
    If fewer shares of OccuSystems Common Stock are voted in favor of the
OccuSystems Proposal, the Concentra Incentive Plan or the Concentra Employee
Stock Purchase Plan than the number required for their approval, it is expected
that the OccuSystems Meeting will be postponed or adjourned for the
 
                                       19
<PAGE>
purpose of allowing additional time for soliciting and obtaining additional
proxies or votes, and, at any subsequent reconvening of the OccuSystems Meeting,
all proxies will be voted in the same manner as such proxies would have been
voted at the original convening of the OccuSystems Meeting, except for any
proxies that have theretofore effectively been revoked or withdrawn.
 
    CRA.  The CRA Board has fixed the close of business on       , 1997, as the
CRA Record Date. Only holders of record of shares of CRA Common Stock on the CRA
Record Date are entitled to notice of and to vote at the CRA Meeting. On       ,
1997, there were       shares of CRA Common Stock outstanding and entitled to
vote at the CRA Meeting held by approximately       stockholders of record.
 
    Each holder of record, as of the CRA Record Date, of CRA Common Stock is
entitled to cast one vote per share. The presence, in person or by proxy, of the
holders of a majority of the outstanding shares of CRA Common Stock entitled to
vote is necessary to constitute a quorum at the CRA Meeting.
 
    Under the MBCL, the affirmative vote, in person or by proxy, of the holders
of two-thirds of the shares of CRA Common Stock outstanding on the CRA Record
Date and entitled to vote on the CRA Proposal is required to approve and adopt
the CRA Proposal. The affirmative vote of the holders of a majority of total
combined shares present and eligible to vote at the CRA Meeting and the
OccuSystems Meeting (after giving effect to the Exchange Ratio to be applied in
the Mergers) is required to approve the Concentra Incentive Plan and the
Concentra Employee Stock Purchase Plan.
 
    As of April 30, 1997, directors and executive officers of CRA as a group
beneficially owned approximately 1,447,347 shares of CRA Common Stock, or
approximately 16.1% of those shares of CRA Common Stock outstanding as of such
date.
 
    If fewer shares of CRA Common Stock are voted in favor of the CRA Proposal,
the Concentra Incentive Plan or the Concentra Employee Stock Purchase Plan than
the number required for their approval, it is expected that the CRA Meeting will
be postponed or adjourned for the purpose of allowing additional time for
soliciting and obtaining additional proxies or votes, and, at any subsequent
reconvening of the CRA Meeting, all proxies will be voted in the same manner as
such proxies would have been voted at the original convening of the CRA Meeting,
except for any proxies that have theretofore effectively been revoked or
withdrawn.
 
PROXIES
 
    OCCUSYSTEMS.  All shares of OccuSystems Common Stock represented by properly
executed proxies received prior to or at the OccuSystems Meeting and not revoked
will be voted in accordance with the instructions indicated in such proxies. If
no instructions are indicated on a properly executed returned proxy, such proxy
will be voted FOR the OccuSystems Proposal, the Concentra Incentive Plan and the
Concentra Employee Stock Purchase Plan. A properly executed proxy marked
"ABSTAIN," although counted for purposes of determining whether there is a
quorum, will not be voted. Accordingly, since the affirmative vote of a majority
of the shares of OccuSystems Common Stock outstanding on the OccuSystems Record
Date is required for approval of the OccuSystems Proposal, a proxy marked
"ABSTAIN" will have the effect of a vote against the OccuSystems Proposal.
Similarly, a proxy marked "ABSTAIN" will have the effect of a vote against the
Concentra Incentive Plan and the Concentra Employee Stock Purchase Plan. In
accordance with the rules of the National Association of Securities Dealers,
Inc. ("NASD"), brokers and nominees are precluded from exercising their voting
discretion on the OccuSystems Proposal, the Concentra Incentive Plan and the
Concentra Employee Stock Purchase Plan and thus, absent specific instructions
from the beneficial owner of such shares, are not empowered to vote such shares.
A broker non-vote (i.e., shares held by brokers or nominees which are
represented at a meeting but with respect to which the broker or nominee is not
empowered to vote) will have the effect of a vote against the OccuSystems
Proposal because the affirmative vote of a majority of the shares of OccuSystems
Common Stock outstanding is required for approval. A broker non-vote will not be
included in the number of shares voting and therefore will have no effect on the
outcome of voting on the Concentra Incentive
 
                                       20
<PAGE>
Plan or the Concentra Employee Stock Purchase Plan. Shares represented by broker
non-votes will, however, be counted for purposes of determining whether there is
a quorum at the OccuSystems Meeting.
 
    CRA.  All shares of CRA Common Stock represented by properly executed
proxies received prior to or at the CRA Meeting and not revoked will be voted in
accordance with the instructions indicated in such proxies. If no instructions
are indicated on a properly executed returned proxy, such proxy will be voted
FOR the CRA Proposal, the Concentra Incentive Plan, and the Concentra Employee
Stock Purchase Plan. A properly executed proxy marked "ABSTAIN," although
counted for purposes of determining whether there is a quorum, will not be
voted. Accordingly, since the affirmative vote of two-thirds of the shares of
CRA Common Stock outstanding on the CRA Record Date is required for approval of
the CRA Proposal, a proxy marked "ABSTAIN" will have the effect of a vote
against the CRA Proposal. Similarly, a proxy marked "ABSTAIN" will have the
effect of a vote against the Concentra Incentive Plan and the Concentra Employee
Stock Purchase Plan. In accordance with the rules of the NASD, brokers and
nominees are precluded from exercising their voting discretion on the CRA
Proposal, the Concentra Incentive Plan and the Concentra Employee Stock Purchase
Plan and thus, absent specific instructions from the beneficial owner of such
shares, are not empowered to vote such shares. A broker non-vote will have the
effect of a vote against the CRA Proposal because the affirmative vote of
two-thirds of the shares of CRA Common Stock outstanding is required for
approval. A broker non-vote will not be included in the number of shares voting
and therefore will have no effect on the outcome of voting on the Concentra
Incentive Plan or the Concentra Employee Stock Purchase Plan. Shares represented
by broker non-votes will, however, be counted for purposes of determining
whether there is a quorum at the CRA Meeting.
 
    It is not expected that any matter not referred to herein will be presented
for action at the OccuSystems Meeting or the CRA Meeting. If any other matters
are properly brought before the OccuSystems Meeting or the CRA Meeting, the
persons named in the proxies will have discretion to vote on such matters in
accordance with their best judgment. However, shares represented by proxies that
have been voted "AGAINST" the OccuSystems Proposal or the CRA Proposal, as the
case may be, will not be used to vote "FOR" postponement or adjournment of the
OccuSystems Meeting or the CRA Meeting, as the case may be, for the purpose of
allowing additional time for soliciting additional votes "FOR" the OccuSystems
Proposal or the CRA Proposal, as the case may be. The grant of a proxy will also
confer discretionary authority on the persons named in the proxy as proxy
appointees to vote in accordance with their best judgment on matters incident to
the conduct of the Special Meetings, including (except as stated in the
preceding sentence) adjournment for the purpose of soliciting additional votes.
 
    GENERAL.  A stockholder of OccuSystems or CRA may revoke his or her proxy at
any time prior to its use by delivering to the Secretary or Clerk of OccuSystems
or CRA, as the case may be, a signed notice of revocation or a later dated
signed proxy or by attending the OccuSystems Meeting or the CRA Meeting and
voting in person. Attendance at the OccuSystems Meeting or the CRA Meeting will
not in itself constitute the revocation of a proxy.
 
    The cost of solicitation of proxies will be paid by OccuSystems for the
OccuSystems proxies and by CRA for the CRA proxies. In addition to solicitation
by mail, proxies may be solicited in person by directors, officers and employees
of OccuSystems or CRA, as the case may be, without additional compensation, and
by telephone, telegram, teletype, facsimile or similar method. Arrangements will
be made with brokerage houses and other custodians, nominees and fiduciaries to
send proxy material to beneficial owners; and OccuSystems or CRA, as the case
may be, will, upon request, reimburse them for their reasonable expenses in so
doing. CRA and OccuSystems have retained       to aid in the solicitation of
proxies at a fee of $         plus expenses. To the extent necessary in order to
ensure sufficient representation at the OccuSystems Meeting or the CRA Meeting,
OccuSystems or CRA, as the case may be, may request by telephone or telegram the
return of proxies. The extent to which this will be necessary depends entirely
upon how promptly proxies are returned.
 
                                       21
<PAGE>
    HOLDERS OF OCCUSYSTEMS COMMON STOCK AND CRA COMMON STOCK SHOULD NOT SEND ANY
CERTIFICATES REPRESENTING OCCUSYSTEMS COMMON STOCK OR CRA COMMON STOCK WITH THE
ENCLOSED PROXY CARD. IF THE MERGERS ARE APPROVED, A LETTER OF TRANSMITTAL WILL
BE MAILED AFTER THE EFFECTIVE TIME TO EACH PERSON WHO WAS A HOLDER OF
OUTSTANDING SHARES OF OCCUSYSTEMS COMMON STOCK OR CRA COMMON STOCK IMMEDIATELY
PRIOR TO THE EFFECTIVE TIME. OCCUSYSTEMS AND CRA STOCKHOLDERS SHOULD SEND
CERTIFICATES REPRESENTING OCCUSYSTEMS COMMON STOCK AND CRA COMMON STOCK TO THE
EXCHANGE AGENT ONLY AFTER THEY RECEIVE, AND IN ACCORDANCE WITH, THE INSTRUCTIONS
CONTAINED IN THE LETTER OF TRANSMITTAL.
 
                                       22
<PAGE>
                                  THE MERGERS
 
BACKGROUND OF THE MERGERS
 
    The terms of the Reorganization Agreement and the related agreements are the
result of arm's-length negotiations between representatives, legal advisers and
financial advisers of CRA and OccuSystems. The following is a brief discussion
of the background of these negotiations.
 
    OccuSystems and CRA commenced discussions regarding a possible transaction
in response to the changes that have occurred and continue to occur within the
healthcare industry in general and the occupational healthcare and managed care
industries in particular. Increasingly, states are expanding the ability of
employers to direct care of injured workers, either directly, or indirectly
through managed care organizations. Employers and insurers are demanding greater
and more detailed information regarding treatment outcomes across the entire
continuum of care. To maintain competitiveness and to control workers'
compensation costs effectively, providers and managed care organizations must
have a broad geographic scope of service coverage and an established primary
care delivery network. Employers and insurers are seeking the benefits of a
single source for occupational healthcare and workers' compensation managed
care-related services. The combination of CRA and OccuSystems provides the
combined company a more balanced growth opportunity with both prospective and
retrospective capabilities, while addressing increased customer demand in the
industry for "one-stop shopping."
 
    In early January, 1996, representatives of Alex. Brown introduced CRA's
Chief Executive Officer, Donald J. Larson, to OccuSystems' Chief Executive
Officer, John K. Carlyle. Subsequently, the two executives had informal
conversations regarding their respective companies' businesses and possible
relationships that might be developed.
 
    On January 29, 1996, Mr. Larson and Mr. Carlyle met in Boston to discuss in
greater detail a business relationship that might be developed between CRA and
OccuSystems. From that time forward, the two executives occasionally held
general discussions concerning the possibility of entering into complementary
business relationships.
 
    As a result of these preliminary discussions, Mr. Carlyle telephoned Mr.
Larson in June of 1996 and invited him to meet with OccuSystems' senior
management. On July 8, 1996, members of CRA's senior management met in Dallas
with senior management of OccuSystems. At this meeting, the parties first
discussed the possibility of a strategic business combination of CRA and
OccuSystems. The respective managements of OccuSystems and CRA determined that
additional discussions regarding the respective business strengths and
operational strategies of the two companies and an exchange of certain non-
confidential information would be useful to facilitate discussions regarding a
possible business combination. Additional discussions and information exchanges
continued thereafter.
 
    At a regularly scheduled board meeting on July 17, 1996, Mr. Larson reviewed
with the CRA Board the substance and status of negotiations with senior
management of OccuSystems.
 
    On August 13 and 14, 1996, members of the senior management of the two
companies met in Chicago to further discuss issues relating to a potential
business combination, including, without limitation, the occupational healthcare
and managed care industries in general, the relative strengths and weaknesses of
the two companies, and an overview of the general business philosophies and
strategies of the two companies. Thereafter, the senior management teams of
OccuSystems and CRA discussed the businesses of the two companies in general and
continued discussions concerning the possibility of various forms of a strategic
transaction between CRA and OccuSystems.
 
    At special telephonic board meetings on August 22 and August 30, 1996, Mr.
Carlyle reviewed with the OccuSystems Board the substance of discussions with
senior management of CRA.
 
    In early September 1996, Mr. Carlyle and Mr. Larson determined that
OccuSystems and CRA would not be able to reach an agreement on acceptable terms
at that time.
 
                                       23
<PAGE>
    From September 1996, to February 1997, the parties had little contact. On
February 11, 1997, Mr. Carlyle and Mr. Larson met in New York and reopened
discussions with respect to a possible business combination between CRA and
OccuSystems.
 
    On February 25, 1997, Mr. Larson met with certain members of senior
management of OccuSystems in Dallas and discussed specific structural issues
related to the proposed business combination, as well as the relative merits of
the proposed business combination.
 
    At a regularly scheduled board meeting on February 26, 1997, and at a
special board meeting on March 17, 1997, Mr. Carlyle reviewed with the
OccuSystems Board the progress of the continuing discussions with CRA.
 
    At a regularly scheduled board meeting on March 14, 1997, Mr. Larson
reviewed with the CRA Board the status and progress of negotiations with
OccuSystems.
 
    On March 19, 1997, CRA and OccuSystems entered into a Confidentiality
Agreement (the "Confidentiality Agreement") pursuant to which they agreed, among
other things, that any confidential information disclosed by one party to the
other would be treated as confidential and would be used solely for the purpose
of evaluating a proposed transaction. Thereafter, the parties exchanged certain
confidential business information for the purpose of further familiarizing each
of the companies with the business and prospects of the other and facilitating
CRA's and OccuSystems' respective due diligence investigations in connection
with the potential business combination.
 
    On March 19 and 20, 1997, the members of CRA's and OccuSystems' senior
management and representatives of Alex. Brown and DLJ met in Dallas to explore
more fully the potential benefits of a possible business combination between CRA
and OccuSystems. OccuSystems' senior management provided certain information and
answered certain questions in furtherance of CRA's due diligence investigation.
Senior management of CRA and OccuSystems became more fully acquainted with the
capabilities of each company and learned in greater detail about the
complementary attributes of their respective businesses and operations.
 
    On March 25 and 26, 1997, the members of OccuSystems and CRA senior
management and representatives of Alex. Brown and DLJ met in Boston. CRA's
senior management provided certain information and answered certain questions in
furtherance of OccuSystems' due diligence investigation. In addition, senior
management of OccuSystems and CRA continued to more fully acquaint themselves
with the capabilities of each company and the complementary nature of their
respective businesses. Subsequently, CRA and OccuSystems continued their
exchange of information in response to each other's diligence requests.
 
    On April 4, 1997, at a special meeting of the CRA Board, Mr. Larson reported
on the status of discussions with OccuSystems' and CRA's continuing due
diligence activities. The CRA Board heard discussions regarding CRA's retention
of an expert to assist in developing a long-term compensation plan for the
combined company. CRA's legal counsel discussed with the CRA Board the structure
of the proposed transaction, potential use of "Concentra Managed Care, Inc." as
the corporate name, and the inclusion of a non-solicitation clause in the
Reorganization Agreement. Mr. Larson also responded to questions regarding the
rationale for the Mergers.
 
    During the period from March 20 through April 8, 1997, senior management of
CRA and OccuSystems had telephone conferences on several occasions to discuss
due diligence matters, the form of a possible transaction and related matters.
Throughout this period, the parties continued their due diligence efforts and
senior management and legal and financial advisers to both companies continued
to discuss structural, procedural, and operational matters with respect to the
proposed transaction.
 
    On April 8, 1997, the members of CRA's and OccuSystems' senior management
and representatives of Alex. Brown and DLJ met in Atlanta to discuss the
potential operational and financial structure of the
 
                                       24
<PAGE>
proposed business combination. The parties also continued their discussions
regarding the healthcare and managed care industries in general and what impact
any proposed business combination would have on the combined company's ability
to compete in this rapidly changing environment.
 
    During the period from April 8 through April 16, 1997, the members of senior
management of OccuSystems and CRA, representatives of Alex. Brown and DLJ, and
the parties' respective legal advisers engaged in extensive discussions and
negotiations to resolve open issues and to establish the terms of a transaction
that could be submitted for consideration to the Boards of Directors of CRA and
OccuSystems.
 
    On April 11, 1997, Mr. Carlyle met in Boston with Lois E. Silverman, a
member of the CRA Board to familiarize the CRA Board members with OccuSystems.
In addition, Mr. Carlyle met with other members of the CRA Board and also met
with members of CRA's senior management, who provided information and answered
questions relevant to OccuSystems' due diligence investigation.
 
    On April 11, 1997, at a special meeting of the CRA Board, Mr. Larson
discussed the proposed organizational chart for the combined company and, with
Joseph F. Pesce, CRA's Chief Financial Officer, discussed in greater detail the
potential cost savings and revenue enhancements from a combination of CRA and
Occusystems. Representatives of Alex. Brown reviewed with the CRA Board the
valuation methodologies to be utilized by Alex. Brown for purposes of its
financial analysis of the proposed transaction and a summary of its due
diligence findings. CRA's legal counsel provided an update on the status of
negotiations regarding the Reorganization Agreement. It was the consensus of the
CRA Board that the proposed business combination offered significant potential
synergies and should be considered further.
 
    On April 16, 1997, at a special meeting of the OccuSystems Board, members of
OccuSystems' senior management, OccuSystems' legal counsel and representatives
of DLJ made presentations to and reviewed with the OccuSystems Board the terms
of the Mergers, the background of the Mergers, OccuSystems' alternatives to the
Mergers, the strategic rationale for and potential benefits of the Mergers, a
summary of due diligence findings, and the status of negotiations. At this
meeting, DLJ made a presentation to the effect that the Exchange Ratio was fair
to the holders of OccuSystems Common Stock from a financial point of view. See
"-- Opinions of Financial Advisors -- Opinion of OccuSystems' Financial
Advisor." After extensive consideration, the OccuSystems Board instructed
OccuSystems' senior management and legal advisers to continue negotiations and
deferred action regarding the Mergers until a special meeting of the OccuSystems
Board to be held on April 21, 1997.
 
    On April 18, 1997, the CRA Board held a special meeting at which members of
CRA's senior management made presentations to and reviewed with the CRA Board
CRA's financial results for the quarter ended March 31, 1997, the status of
continuing negotiations with OccuSystems, various compensation issues, and
details regarding CRA senior management's plan for effective integration of the
combined companies. CRA's legal counsel discussed the Stock Option Agreements to
be signed by the companies and responded to questions from various directors.
Representatives of Alex. Brown indicated that, subject to review of the final
documentation for the Mergers, they believed Alex. Brown would be in a position
to render a fairness opinion with respect to the proposed Exchange Ratio.
 
    On the afternoon of April 21, 1997, the CRA Board held a special telephonic
meeting to consider and vote upon the Mergers. Following presentations by
members of CRA's senior management and financial and legal advisors, including
Alex. Brown's delivery of its opinion (see "-- Opinions of Financial Advisors --
Opinion of CRA's Financial Advisor"), and a summary of the results of the
negotiations, the CRA Board determined by a unanimous vote of directors (i) that
the transactions contemplated by the Reorganization Agreement were in the best
interests of CRA, and (ii) that the Exchange Ratio is fair, from a financial
point of view, to CRA. Subsequently, the CRA Board adopted and approved the
Reorganization Agreement and the transactions contemplated thereby.
 
                                       25
<PAGE>
    Also on the afternoon of April 21, 1997, the OccuSystems Board held a
special meeting to consider and vote upon the Mergers. The OccuSystems Board
approved by a unanimous vote the Reorganization Agreement and the transactions
contemplated thereby. See "-- Opinions of Financial Advisors -- Opinion of
OccuSystems' Financial Advisor."
 
    On the evening of April 21, 1997, Concentra, OccuSystems, and CRA executed
the Reorganization Agreement and CRA and OccuSystems entered into the Stock
Option Agreements.
 
RECOMMENDATION OF OCCUSYSTEMS BOARD; OCCUSYSTEMS' REASONS FOR THE MERGERS
 
    THE OCCUSYSTEMS BOARD UNANIMOUSLY RECOMMENDS THAT HOLDERS OF OCCUSYSTEMS
COMMON STOCK VOTE FOR THE OCCUSYSTEMS PROPOSAL.
 
    The OccuSystems Board believes that the terms of the Reorganization
Agreement and the transactions contemplated thereby are in the best interests of
OccuSystems and its stockholders. Accordingly, the OccuSystems Board has
unanimously approved the Reorganization Agreement and recommends approval of the
OccuSystems Proposal by the stockholders of OccuSystems.
 
    In view of the variety of factors considered in connection with its
evaluation of the Mergers, the OccuSystems Board did not quantify or otherwise
attempt to assign relative weights to the specific factors considered in
reaching its determination.
 
    In reaching its determination to recommend approval of the OccuSystems
Proposal, the OccuSystems Board consulted with OccuSystems management, as well
as its legal counsel and financial advisor, and considered a number of factors.
The OccuSystems Board reviewed the complementary nature of the businesses of the
two companies, which present opportunities for cross-utilization and
cross-promotion of operations and assets of each company in the businesses
operated by the other. The OccuSystems Board considered that the quality of CRA
management and the complementary nature of the two companies' businesses create
significant opportunities for development of the companies on a combined basis
without the need for significant restructuring, redirection or asset
dispositions. In addition, the OccuSystems Board considered the administrative
cost savings and potential synergies (such as the ability to serve CRA customers
through OccuSystems' centers, field and telephone access to CRA's case
management systems by OccuSystems' affiliated physicians and the opportunity for
a comprehensive response to injury through the combination of OccuSystems'
resources and CRA's PPO participants) that are expected to result in earnings in
excess of the individual financial performances of the two companies.
 
    The OccuSystems Board considered a number of factors, including the
following, in determining that the Mergers would be consistent with, and
contribute to the fulfillment of, OccuSystems' strategy:
 
    - The Mergers should establish Concentra as the premier managed care company
      in the workers' compensation and disability marketplace, offering the
      broadest spectrum of services in the industry.
 
    - CRA's broad geographic scope of operations throughout the United States
      and long-standing relationships with large insurers and self-insured
      employers should facilitate OccuSystems' strategy to continue to
      consolidate primary care physician practices specializing in occupational
      healthcare in new and existing markets and to develop clusters of
      occupational healthcare centers.
 
    - CRA's and OccuSystems' information systems, outcomes and cost data will
      provide Concentra with access to information across the entire continuum
      of care for work related injuries. This should strengthen Concentra's
      ability to market its medical services on a case rate and capitated basis.
 
    - CRA's PPO and expertise in case management services should strengthen
      OccuSystems' ability to develop vertically integrated networks of
      providers.
 
    - CRA's expertise in case management and specialized cost containment
      services should enhance OccuSystems' proprietary injury/illness management
      program.
 
                                       26
<PAGE>
    The OccuSystems Board reviewed a financial comparison of OccuSystems and CRA
and analyzed OccuSystems' contribution to the pro forma revenues, cash flows and
net income of Concentra. The OccuSystems Board studied the potential effect on
the earnings per share of the new combined company as a result of the Mergers.
The OccuSystems Board also took into account the historical performance of the
common stock of each of OccuSystems and CRA.
 
    The OccuSystems Board considered that Concentra will have a substantially
larger market capitalization than OccuSystems and that OccuSystems' stockholders
should enjoy enhanced liquidity as a result of Concentra's larger stockholder
base and increased visibility.
 
    The OccuSystems Board considered the terms and conditions of the
Reorganization Agreement, including the amount and form of consideration to be
received by the stockholders of OccuSystems.
 
    The OccuSystems Board considered the provisions of the Reorganization
Agreement that prohibit CRA and its subsidiaries, and their respective
directors, officers, employees and representatives, from soliciting or
encouraging any CRA Alternative Proposals or, subject to the fiduciary duties of
the CRA Board, from negotiating with any third parties with respect to a CRA
Alternative Proposal. The OccuSystems Board further considered the provisions of
the Reorganization Agreement that require CRA to pay to OccuSystems a fee of $10
million if a CRA Alternative Proposal is made and thereafter the Reorganization
Agreement is terminated by action of the CRA Board in the exercise of its
fiduciary duties by reason of such CRA Alternative Proposal or by action of
OccuSystems if the CRA Board has withdrawn or modified in a manner materially
adverse to OccuSystems its approval or recommendation of the CRA Proposal. See
"THE REORGANIZATION AGREEMENT -- Termination of the Reorganization Agreement"
and "-- Termination Fees."
 
    The OccuSystems Board considered the terms of the CRA Stock Option
Agreement, pursuant to which, among other things, CRA granted OccuSystems an
option to purchase up to ten percent of the outstanding CRA Common Stock. See
"THE STOCK OPTION AGREEMENTS."
 
    The OccuSystems Board considered that the Mergers will be accounted for
under the pooling of interests method of accounting and will be a tax-free
reorganization for federal income tax purposes. See "--Accounting Treatment" and
"--Certain Federal Income Tax Consequences."
 
    The OccuSystems Board considered the presentation of DLJ made at the
OccuSystems Board meeting held on April 16, 1997 (and subsequently confirmed in
a written opinion dated April 21, 1997), to the effect that the Exchange Ratio
was fair to the holders of OccuSystems Common Stock from a financial point of
view. See "-- Opinions of Financial Advisors -- Opinion of OccuSystems'
Financial Advisor."
 
RECOMMENDATION OF CRA BOARD; CRA'S REASONS FOR THE MERGERS
 
    THE CRA BOARD UNANIMOUSLY RECOMMENDS THAT HOLDERS OF CRA COMMON STOCK VOTE
FOR THE CRA PROPOSAL.
 
    The CRA Board believes that the terms of the Reorganization Agreement and
the transactions contemplated thereby are in the best interests of CRA and its
stockholders. Accordingly, the CRA Board has unanimously approved the
Reorganization Agreement and recommends that the stockholders of CRA vote for
the approval and adoption of the Reorganization Agreement and the transactions
contemplated thereby.
 
    In reaching its determination to approve the Reorganization Agreement, the
CRA Board considered numerous factors, including, without limitation, the
factors identified below. In reaching its determination, the CRA Board consulted
with CRA management, as well as CRA's legal counsel and financial advisor. In
light of the variety of factors considered in connection with its evaluation of
the Reorganization Agreement, the CRA Board did not consider it practicable to,
nor did it attempt to, quantify or otherwise assign relative weights to the
specific factors it considered in reaching its determination.
 
                                       27
<PAGE>
    The CRA Board believes that the combination of CRA and OccuSystems is a
major step forward in the pursuit of CRA's strategic objective of becoming the
premier managed care services company for the workers' compensation and
disability marketplaces. Among other factors, the CRA Board considered the
following strategic reasons for the Mergers:
 
    - The ability to leverage OccuSystems' primary care expertise at the point
      of injury to influence the direction of care, as appropriate.
 
    - The ability to combine the strengths of national leaders in the workers'
      compensation and disability industries so as to create one national leader
      offering the broadest spectrum of services, which is increasingly being
      demanded by the marketplace.
 
    - The complementary nature of the business of CRA and OccuSystems, including
      the complementary nature of CRA's insurance-oriented customer base and
      OccuSystems' employer-oriented customer base.
 
    - The potential to utilize statistical information concerning the full
      spectrum of CRA's and OccuSystems' services made possible by both
      companies' investment in substantially compatible information technology.
 
    - The prospect of a combined company that will have a significantly larger
      market capitalization than CRA, and the resulting potential for greater
      liquidity for stockholders.
 
    - The potential for administrative cost savings and business synergies which
      the CRA Board believes could result from a combined company, including
      potentially better utilization or expansion of OccuSystems' network of
      treatment centers and a primary physician network that could be used by
      CRA to offer new fully integrated products to its customers.
 
    In reaching its conclusions, the CRA Board also considered, among other
things, (i) information concerning the financial performance, condition,
business operation and prospects of each of CRA and OccuSystems, (ii) the
historical performance of the common stock of CRA and OccuSystems, (iii) the
terms and conditions of the Reorganization Agreement, including the amount and
form of consideration to be received by the stockholders of CRA, the
restrictions relating to solicitation of third party proposals, including the
provisions that prohibit OccuSystems and its subsidiaries, and their respective
directors, officers, employees and representatives, from soliciting or
encouraging any OccuSystems Alternative Proposals or, subject to the fiduciary
duties of the OccuSystems Board, from negotiating with any third parties with
respect to an OccuSystems Alternative Proposal, the termination provisions and
the size, nature and events that would trigger the payment of the $10 million
termination fee contained in the Reorganization Agreement (See "THE
REORGANIZATION AGREEMENT -- Termination of the Reorganization Agreement" and "--
Termination Fees."), (iv) the terms and conditions of the Stock Option
Agreements, (v) that the transaction would be tax-free for CRA and the CRA
stockholders, and (vi) that the Mergers will be accounted for under the pooling
of interests method of accounting and the impact that such accounting treatment
would have on the earnings per share of Concentra. The CRA Board also considered
the opinion of Alex. Brown described below, and the financial analyses performed
by Alex. Brown in connection therewith. See "-- Opinion of Financial Advisors --
Opinion of CRA's Financial Advisor."
 
OPINIONS OF FINANCIAL ADVISORS
 
    OPINION OF OCCUSYSTEMS' FINANCIAL ADVISOR
 
    On March 27, 1997, OccuSystems engaged DLJ to act as its exclusive financial
advisor in connection with the Reorganization Agreement. On April 16, 1997, DLJ
made a presentation to the OccuSystems Board, which DLJ confirmed by delivery of
its written opinion dated April 21, 1997 (the "DLJ Opinion"), to the effect
that, as of April 21, 1997, and based upon and subject to the assumptions,
limitations and
 
                                       28
<PAGE>
qualifications set forth in its opinion, the Exchange Ratio was fair to the
holders of OccuSystems Common Stock from a financial point of view.
 
    THE FULL TEXT OF THE DLJ OPINION IS SET FORTH AS ANNEX D TO THIS JOINT PROXY
STATEMENT/PROSPECTUS AND SHOULD BE READ CAREFULLY IN ITS ENTIRETY FOR A
DISCUSSION OF THE ASSUMPTIONS MADE, PROCEDURES FOLLOWED, OTHER MATTERS
CONSIDERED AND LIMITS OF THE REVIEW BY DLJ.
 
    The DLJ Opinion was prepared for the OccuSystems Board and addresses only
the fairness of the Exchange Ratio to the holders of OccuSystems Common Stock
from a financial point of view and does not constitute a recommendation to any
stockholder of OccuSystems as to how such stockholder should vote at the
OccuSystems Meeting. The DLJ Opinion does not constitute an opinion as to the
price at which Concentra Common Stock will actually trade at any time. The type
and amount of consideration for the Mergers was determined in arms' length
negotiations between OccuSystems and CRA. DLJ advised OccuSystems in the
negotiations. OccuSystems did not impose any restrictions or limitations on DLJ
with respect to the investigations made or procedures followed by DLJ in
rendering its opinion. OccuSystems did not request DLJ to, nor did DLJ, solicit
the interest of any other party in acquiring OccuSystems.
 
    In arriving at the DLJ Opinion, DLJ reviewed drafts of the Reorganization
Agreement, the OccuSystems Stock Option Agreement and the CRA Stock Option
Agreement. DLJ also reviewed financial and other information that was publicly
available or furnished to DLJ by OccuSystems and CRA, including information
provided during discussions with their respective managements. This information
included financial projections of OccuSystems for the period beginning January
1, 1997, and ending on December 31, 2001, prepared by the management of
OccuSystems, and financial projections of CRA for the period beginning January
1, 1997, and ending on December 31, 2001, prepared by the management of CRA. In
addition, DLJ compared certain financial and securities data of OccuSystems and
CRA with various other companies that DLJ deemed to be relevant whose securities
are traded in public markets, reviewed the historical stock prices and trading
volumes of OccuSystems Common Stock and CRA Common Stock and reviewed such other
financial studies and analyses, and performed such other investigations, as DLJ
deemed appropriate for purposes of its opinion.
 
    In rendering its opinion, DLJ relied upon and assumed the accuracy and
completeness of all of the financial and other information that was available
from public sources, that was provided by OccuSystems and CRA or their
respective representatives, or that was otherwise reviewed by DLJ. In
particular, DLJ relied upon the estimates of the management of OccuSystems of
the operating synergies achievable as a result of the Mergers (the "Operating
Synergies"), which DLJ discussed with the management of CRA. With respect to the
financial projections supplied to DLJ, DLJ assumed that such projections were
reasonably prepared on the basis reflecting the best currently available
estimates and judgments of the management of OccuSystems and CRA as to the
future operating and financial performance of OccuSystems and CRA, respectively.
DLJ did not assume any responsibility for making an independent evaluation of
OccuSystems' assets or liabilities or for making any independent verification of
any of the information reviewed by DLJ.
 
    The DLJ Opinion was necessarily based on economic, market, financial and
other conditions as they existed on, and on the information made available to
DLJ as of, the date of the DLJ Opinion. The following is a summary of the
presentation made by DLJ to the OccuSystems Board at the meeting on April 16,
1997.
 
                                       29
<PAGE>
    CONTRIBUTION ANALYSIS.  DLJ analyzed the relative contributions of
OccuSystems and CRA to revenues, earnings before interest, taxes, depreciation
and amortization ("EBITDA"), earnings before interest and taxes ("EBIT"),
pre-tax income and net income, as if OccuSystems and CRA were a combined entity.
Such analysis was completed for various periods of time, including among others,
for calendar year 1996, after giving pro forma effect to CRA's Focus Healthcare
Management, Inc., Prompt Associates, Inc. and QMC3, Inc. acquisitions, as if
each acquisition had occurred on January 1, 1996 ("Pro Forma 1996"), and for the
projected calendar years 1997 and 1998. Based on Pro Forma 1996, OccuSystems'
revenues, EBITDA, EBIT, pre-tax income and net income represent 46.6%, 54.5%,
52.1%, 49.1% and 52.2%, respectively, of the combined entity. Based on projected
1997, OccuSystems' revenues, EBITDA, EBIT, pre-tax income and net income
represent 48.6%, 58.3%, 56.4%, 52.6% and 56.3%, respectively, of the combined
entity. Based on projected 1998, OccuSystems' revenues, EBITDA, EBIT, pre-tax
income and net income represent 51.4%, 61.9%, 60.4%, 57.2% and 59.3%,
respectively, of the combined entity. The shares of Concentra Common Stock
(including shares underlying all outstanding options, calculated using the
treasury method) to be issued to the holders of OccuSystems Common Stock in
accordance with the Exchange Ratio represents approximately 57.8% of the
outstanding shares of Concentra Common Stock pro forma for the Mergers (the
"OccuSystems Ownership Percentage"), based on the number of shares of
OccuSystems Common Stock and CRA Common Stock outstanding in March 1997.
 
    EARNINGS PER SHARE IMPACT ANALYSIS.  DLJ analyzed the pro forma effects on
OccuSystems' earnings per share ("EPS") of the Mergers, including the Operating
Synergies as forecasted by the management of OccuSystems, for various periods of
time, including among others, for Pro Forma 1996 and projected calendar years
1997 and 1998. This analysis was based on a number of assumptions, including
among other things, the cost of integrating the operations of OccuSystems and
CRA, estimated amounts and timing of implementation of the Operating Synergies,
the projected financial performance of OccuSystems and CRA and prevailing
interest rates. The analysis indicated that the Mergers, accounted for as a
pooling of interests, with the benefit of the Operating Synergies but excluding
one-time expenses related to the Mergers, is accretive to OccuSystems'
stand-alone EPS for each of Pro Forma 1996 and projected calendar years 1997 and
1998.
 
    HISTORICAL TRADING RELATIONSHIP.  DLJ analyzed the historical trading
relationship of CRA Common Stock and OccuSystems Common Stock over the time
periods noted below. For each period selected, the high, low and average ratios
were calculated by dividing the closing price of CRA Common Stock by the closing
price of OccuSystems Common Stock for each day during such period. The time
periods (each ending April 15, 1997) selected for analysis were as follows: last
12 months, last 120 trading days, last 60 trading days, last 20 trading days,
last ten trading days, last five trading days and at the close of trading on
April 15, 1997. The average ratios or actual ratio, as the case may be, of the
closing price of CRA Common Stock to those of OccuSystems Common Stock for each
of the aforementioned time periods or days were 1.6332, 1.8167, 1.8848, 1.8366,
1.9669, 2.1083 and 2.1060, respectively.
 
    DISCOUNTED CASH FLOW ANALYSIS.  DLJ performed a discounted cash flow ("DCF")
analysis for the five-year period ended December 31, 2001 on the stand-alone,
unlevered free cash flows of OccuSystems and Concentra, which were based upon
financial projections provided by OccuSystems' management and CRA's management
and which included the Operating Synergies. The unlevered free cash flows were
calculated for each of OccuSystems and Concentra based on projected EBIT minus
income taxes, minus projected capital expenditures, plus or minus projected
changes in working capital and plus projected depreciation and amortization
expenses. DLJ calculated terminal values by applying a range of EBITDA multiples
of 8.0x to 12.0x to the projected calendar year 2001 EBITDA of OccuSystems and
Concentra, respectively. The equity value was determined by discounting the
unlevered free cash flows and terminal values to the present using a range of
discount rates of 11.0% to 15.0%, representing an estimated range of the
weighted average cost of capital of each of OccuSystems and Concentra. DLJ then
applied the
 
                                       30
<PAGE>
OccuSystems Ownership Percentage to the DCF analysis of Concentra to establish
the value of OccuSystems stockholders' interest in Concentra. Based on this
analysis, DLJ calculated equity values of OccuSystems stand-alone ranging from
$476.3 million to $883.1 million and of OccuSystems stockholders' interest in
Concentra ranging from $497.5 million to $884.9 million.
 
    The summary set forth above does not purport to be a complete description of
the analyses performed by DLJ, but describes, in summary form, the principal
elements of the presentation made by DLJ to the OccuSystems Board on April 16,
1997. The preparation of a fairness opinion involves various judgments as to
appropriate methods of financial analysis to be applied to particular
circumstances and, therefore, such an opinion is not readily susceptible to
summary description. Each of the analyses conducted by DLJ was carried out in
order to provide a different perspective on the transaction and add to the total
mix of information available. DLJ did not conclude whether any individual
analysis, considered in isolation, supported or failed to support an opinion as
to the fairness of the Exchange Ratio from a financial point of view. Rather, in
reaching its conclusion, DLJ considered the results of each analysis in light of
each other and ultimately reached its opinion based on the results of its
analyses taken as a whole. DLJ did not place particular reliance or weight on
any individual analysis, but instead concluded that its analyses, taken as a
whole, supported its determination. Accordingly, notwithstanding the separate
factors summarized above, DLJ believes that its analyses must be considered as a
whole and that selecting portions of its analyses and the factors considered by
it, without considering all analyses and factors, could create an incomplete or
misleading view of the evaluation process underlying its opinion. In performing
its analyses, DLJ made numerous assumptions with respect to industry
performance, business and economic conditions and other matters. The analyses
performed by DLJ are not necessarily indicative of actual value or future
results, which may be significantly more or less favorable than suggested by
such analyses.
 
    RELATIONSHIP BETWEEN OCCUSYSTEMS, CRA AND DLJ.  DLJ is a nationally
recognized investment banking firm that has substantial experience in health
care related businesses and is familiar with OccuSystems, CRA and their
respective businesses. As part of its investment banking business, DLJ is
regularly engaged in the valuation of businesses and securities in connection
with mergers, acquisitions, underwritings, sales and distributions of listed and
unlisted securities, private placements and valuations for estate, corporate and
other purposes.
 
    Pursuant to the letter agreement, dated March 27, 1997, between OccuSystems
and DLJ (the "DLJ Engagement Letter"), DLJ received a fee of $800,000 at the
time OccuSystems requested DLJ to deliver its opinion to the OccuSystems Board
and is entitled to (i) an additional fee of $50,000 for each update of the DLJ
Opinion delivered by DLJ to the OccuSystems Board and (ii) a transaction fee
equal to $1,800,000 (less any other fees paid pursuant to the DLJ Engagement
Letter) payable upon consummation of the Mergers. In addition, OccuSystems has
agreed to reimburse DLJ for certain out-of-pocket expenses, and to indemnify DLJ
for certain liabilities and expenses, arising out of the Mergers or the
transactions in connection therewith, including liabilities under federal
securities laws. The terms of the fee arrangement with DLJ, which OccuSystems
and DLJ believe are customary in transactions of this nature, were negotiated at
arms' length between OccuSystems and DLJ, and the OccuSystems Board was aware of
such arrangement, including the fact that a significant portion of the aggregate
fee payable to DLJ is contingent upon consummation of the Mergers.
 
    DLJ has performed investment banking and other services for OccuSystems in
the past and has been compensated for such services. Those services have
included serving as (i) lead manager of OccuSystems' initial public offering in
May 1995, (ii) lead manager of a secondary equity offering in March 1996 and
(iii) lead manager of a convertible subordinated notes offering in December
1996, in each case, for which DLJ received usual and customary compensation. In
addition, an affiliate of DLJ has invested an aggregate of $12.5 million in debt
and equity securities of Concentra Development Corp., an entity to which
OccuSystems provides certain management and administrative services.
 
                                       31
<PAGE>
    In the ordinary course of business, DLJ actively trades debt and equity
securities of OccuSystems for its own account and for the accounts of its
customers and, accordingly, may at any time hold a long or short position in
such securities.
 
    OPINION OF CRA'S FINANCIAL ADVISOR
 
    CRA engaged Alex. Brown to act as its exclusive financial advisor in
connection with the Mergers. On April 21, 1997, at a meeting of the CRA Board
held to evaluate the proposed Mergers, Alex. Brown rendered to the CRA Board an
opinion to the effect that, as of such date and based upon and subject to
certain matters stated in such opinion, the Exchange Ratio was fair from a
financial point of view to the holders of CRA Common Stock. No limitations were
imposed by the CRA Board upon Alex. Brown with respect to the investigations
made or the procedures followed by it in rendering its opinion.
 
    The full text of the written opinion of Alex. Brown dated April 21, 1997,
which sets forth the assumptions made, matters considered and limitations of the
review undertaken, is attached as Appendix E to this Joint Proxy
Statement/Prospectus and should be read carefully in its entirety. Alex. Brown's
opinion is directed to the CRA Board, addresses only the fairness of the
Exchange Ratio from a financial point of view and does not constitute a
recommendation to any stockholder as to how such stockholder should vote at the
CRA Meeting. The summary of the opinion of Alex. Brown set forth in this Joint
Proxy Statement/ Prospectus is qualified in its entirety by reference to the
full text of such opinion.
 
    In connection with its opinion, Alex. Brown reviewed certain publicly
available financial information and other information concerning CRA and
OccuSystems and certain internal analyses and other information furnished to
Alex. Brown by CRA and OccuSystems. Alex. Brown also held discussions with
members of the senior managements of CRA and OccuSystems regarding the
businesses and prospects of their respective companies and the joint prospects
of a combined company. In addition, Alex. Brown (i) reviewed the reported prices
and trading activity for both the CRA Common Stock and OccuSystems Common Stock,
(ii) compared certain financial and stock market information for CRA and
OccuSystems with similar information of certain other companies whose securities
are publicly traded, (iii) reviewed the financial terms of recent business
combinations which Alex. Brown deemed comparable in whole or in part, and (iv)
performed such other studies and analyses and considered such other factors as
Alex. Brown deemed appropriate.
 
    As described in its opinion, Alex. Brown assumed and relied upon, without
independent verification, the accuracy, completeness and fairness of the
information furnished to or otherwise reviewed by or discussed with Alex. Brown
for purposes of its opinion. With respect to the information relating to the
prospects of CRA and OccuSystems, Alex. Brown assumed that such information
reflected the best currently available judgments and estimates of the
managements of CRA and OccuSystems as to the likely future financial
performances of their respective companies and of the combined company. Alex.
Brown did not make nor was it provided with an independent evaluation or
appraisal of the assets of CRA and OccuSystems. Alex. Brown's opinion was based
on market, economic and other conditions as they existed and could be evaluated
as of the date of the opinion. Although Alex. Brown evaluated the Exchange Ratio
from a financial point of view, the type and amount of consideration payable in
the Mergers was determined through negotiation between CRA and OccuSystems.
Alex. Brown's opinion does not constitute an opinion as to the price at which
the Concentra Common Stock will actually trade at any time.
 
    The following is a summary of the material analyses and factors considered
by Alex. Brown in connection with its opinion to the CRA Board dated April 21,
1997:
 
    STOCK TRADING HISTORY.  Alex. Brown reviewed the historical trading volumes
and market prices for the CRA Common Stock and the OccuSystems Common Stock and
the implied historical exchange ratio of the CRA Common Stock and the
OccuSystems Common Stock (the closing price of the OccuSystems Common Stock
divided by the closing price of the CRA Common Stock) based on such market
prices as of the 10 trading days, 20 trading days, three-month period and
six-month period preceding April 18, 1997
 
                                       32
<PAGE>
(the last trading day prior to the execution of the Reorganization Agreement).
This analysis indicated average exchange ratios for the CRA Common Stock and the
OccuSystems Common Stock as of the 10 trading days, 20 trading days, three-month
period and six-month period preceding April 18, 1997 of approximately 0.48,
0.53, 0.53 and 0.55, respectively, as compared to the OccuSystems Exchange Ratio
divided by the CRA Exchange Ratio, which equates to 0.56.
 
    CONTRIBUTION ANALYSIS.  Alex. Brown analyzed the relative contributions of
CRA and OccuSystems to the estimated revenues, EBITDA, EBIT and net income of
Concentra for the latest 12 months ended December 31, 1996, the estimated
revenues, EBITDA and net income of Concentra for fiscal 1997, and the estimated
net income of Concentra for fiscal 1998 and 1999, based on internal estimates of
the managements of CRA and OccuSystems, and compared such contributions to the
pro forma ownership of Concentra by the holders of CRA Common Stock. This
analysis indicated that (i) for the latest 12 months ended December 31, 1996,
CRA would have contributed approximately 51% of the revenues, 43% of EBITDA, 47%
of EBIT and 48% of the net income of Concentra, (ii) in fiscal 1997, CRA would
contribute approximately 51% of the revenues, 43% of EBITDA and 44% of the net
income of Concentra and (iii) in fiscal 1998 and 1999, CRA would contribute
approximately 41% and 39%, respectively, of the net income of Concentra. Based
on the Exchange Ratio, current holders of CRA Common Stock would own
approximately 42% of Concentra upon consummation of the Mergers.
 
    EARNINGS PER SHARE IMPACT ANALYSIS.  Alex. Brown analyzed the pro forma
effect of the Mergers on the EPS of CRA in fiscal 1997 (pro forma as if the
Mergers had occurred on January 1, 1997), 1998 and 1999, based on internal
estimates of the management of CRA and OccuSystems and assuming certain cost
savings and other potential synergies anticipated by such managements to result
from the Mergers were achieved. This analysis indicated that the Mergers could
be slightly dilutive to CRA's EPS in 1997 (pro forma) and accretive to CRA's EPS
in fiscal 1998 and 1999. The actual operating or financial results achieved by
Concentra may vary from projected results and variations may be material as a
result of business and market risks, the timing and amount of synergies, the
costs associated with achieving such synergies and other factors.
 
    DISCOUNTED CASH FLOW ANALYSIS.  Alex. Brown performed a discounted cash flow
analysis of OccuSystems to estimate the present value of the stand-alone,
unlevered, after-tax free cash flows that OccuSystems could generate over the
five-year period ending December 31, 2001, based on internal estimates of the
management of OccuSystems. After-tax cash flows were calculated as the after-tax
EBIT of OccuSystems, plus depreciation and amortization, less net investment in
non-cash working capital, capital expenditures and expenditures for
acquisitions. Terminal values for OccuSystems were calculated by applying
multiples ranging from 10.0x to 15.0x to the projected EBITDA of OccuSystems.
The cash flow streams and terminal values were then discounted to present value
utilizing discount rates ranging from 12.5% to 17.5%. This analysis yielded an
equity reference range for OccuSystems of between $21.32 and $41.25 per share.
 
    ANALYSIS OF SELECTED MERGERS OF EQUALS TRANSACTIONS.  Alex. Brown reviewed
certain merger of equals transactions which it deemed comparable in whole or in
part to the Mergers, based on, among other things, relative market values; pro
forma ownership; relative exchange ratios; historical stock price movements; and
composition of management and board of directors. Specifically, Alex. Brown
reviewed the following 17 transactions which resulted in equal representation of
each company on the board of directors of the combined company: Morgan Stanley
Group, Inc./Dean Witter, Discover & Co.; Morton International/Autoliv AB;
Applied Bioscience International, Inc./Pharmaceutical Product Development, Inc.;
NYNEX Corporation/Bell Atlantic Corporation; Pharmacia AB/The Upjohn Company;
Scott Paper Company/Kimberly-Clark Corporation; Abbey Healthcare Group,
Inc./Homedco Group, Inc.; Vestar, Inc./ Nexagen, Inc.; Dibrill Brothers,
Inc./Monk-Austin, Inc.; Lockheed Corporation/Martin Marietta Corporation;
Babbage's Inc./Software Etc. Stores, Inc.; Synoptics Communications/Wellfleet
Communications, Inc.; Price Company/Costco Wholesale Corp.; Critical Care
America, Inc./Medical Care International,
 
                                       33
<PAGE>
Inc.; Iowa Resources, Inc./Midwest Energy Company; Morino, Inc./Duquesne
Systems, Inc.; and Teleconnect, Inc./SouthernNet, Inc. (the "Selected
Transactions"). Alex. Brown calculated the percentage premium or discount of the
exchange ratios in the Selected Transactions relative to the stock market prices
of the companies involved in the Selected Transactions 30 days prior to public
announcement of the Selected Transaction. Alex. Brown compared the average
premium paid by the company whose chief executive officer continued as the chief
executive officer of the combined company with the implied premium payable in
the Mergers. This analysis indicated a range of premiums (excluding outliers) in
the Selected Transactions of approximately (15%) to 33% (with an average of 8%),
as compared to a premium of approximately 2% to 16% in the Mergers based on
historical exchange ratios of the CRA Common Stock and the OccuSystems Common
Stock over various periods ending April 18, 1997.
 
    HISTORICAL AND PRO FORMA COMPARISON.  In rendering its opinion, Alex. Brown
also reviewed, among other things, (i) the historical and pro forma financial
profile of CRA, OccuSystems and Concentra, (ii) movements in the CRA Common
Stock, the OccuSystems Common Stock and the S&P 500 Index, (iii) the historical
and pro forma equity values and trading multiples of CRA and OccuSystems and
other physician practice management and specialty managed care companies, (iv)
growth rate estimates of selected investment banking firms with respect to CRA,
OccuSystems and other physician practice management and specialty managed care
companies and (v) the pro forma ownership of Concentra.
 
    The summary set forth above does not purport to be a complete description of
the opinion of Alex. Brown to the CRA Board of Directors or the financial
analyses performed and factors considered by Alex. Brown in connection with its
opinion. The preparation of a fairness opinion is a complex analytic process
involving various determinations as to the most appropriate and relevant methods
of financial analyses and the application of those methods to the particular
circumstances and, therefore, such an opinion is not readily susceptible to
summary description. Alex. Brown believes that its analyses and the summary set
forth above must be considered as a whole and that selecting portions of its
analyses, without considering all analyses, or selecting portions of the above
summary, without considering all factors and analyses, could create a misleading
or incomplete view of the processes underlying such analyses and opinion. In
performing its analyses, Alex. Brown made numerous assumptions with respect to
industry performance, general business, economic, market and financial
conditions and other matters, many of which are beyond the control of CRA and
OccuSystems. No company, transaction or business used in such analyses as a
comparison is identical to CRA, OccuSystems, Concentra or the proposed Mergers,
nor is an evaluation of the results of such analyses entirely mathematical;
rather, such analyses involve complex considerations and judgments concerning
financial and operating characteristics and other factors that could affect the
acquisition, public trading or other values of the companies, business segments
or transactions being analyzed. The estimates contained in such analyses and the
ranges of valuations resulting from any particular analysis are not necessarily
indicative of actual values or future results, which may be significantly more
or less favorable than those suggested by such analyses. In addition, analyses
relating to the value of businesses or securities do not purport to be
appraisals or to reflect the prices at which businesses or securities actually
may be sold. Accordingly, such analyses and estimates are inherently subject to
substantial uncertainty. Alex. Brown's opinion and financial analyses were only
one of many factors considered by the CRA Board in its evaluation of the
proposed Mergers and should not be viewed as determinative of the views of the
CRA Board or management with respect to the Exchange Ratio or the Mergers.
 
    RELATIONSHIP BETWEEN CRA, OCCUSYSTEMS AND ALEX. BROWN.  Alex. Brown is a
nationally recognized investment banking firm and, as a customary part of its
investment banking business, is engaged in the valuation of businesses and their
securities in connection with mergers and acquisitions, negotiated
underwritings, private placements and valuations for estate, corporate and other
purposes. CRA selected Alex. Brown to serve as its financial advisor based on
Alex. Brown's reputation and health care expertise as well as its familiarity
with CRA, OccuSystems and their respective businesses. In the past, Alex. Brown
has provided financial advisory services to CRA and has acted as lead-managing
underwriter with respect to
 
                                       34
<PAGE>
CRA Common Stock offerings. Alex. Brown also has acted as co-managing
underwriter with respect to OccuSystems Common Stock and OccuSystems Notes
offerings. Alex. Brown maintains a market in CRA Common Stock and OccuSystems
Common Stock and regularly publishes research reports regarding the health care
industry and the businesses and securities of CRA and OccuSystems and other
publicly-owned companies in that industry. In the ordinary course of business,
Alex. Brown may actively trade the securities of both CRA and OccuSystems for
its own account and the accounts of its customers and, accordingly, may at any
time hold a long or short position in securities of CRA and OccuSystems.
 
    Pursuant to the terms of Alex. Brown's engagement, CRA has agreed to pay
Alex. Brown for its financial advisory services in connection with the Mergers
an aggregate fee of $3.8 million, including a fee of $750,000 payable in
connection with the delivery of Alex. Brown's opinion. In addition, CRA has
agreed to reimburse Alex. Brown for its reasonable out-of-pocket expenses,
including fees and disbursements of counsel, and to indemnify Alex. Brown and
certain related parties against certain liabilities, including certain
liabilities under the federal securities laws, relating to, or arising out of,
its engagement.
 
INTERESTS OF CERTAIN PERSONS IN THE MERGERS
 
    In considering the respective recommendations of the OccuSystems Board and
the CRA Board with respect to the Reorganization Agreement and the transactions
contemplated thereby, stockholders of OccuSystems and CRA should be aware that
certain members of the management of OccuSystems and CRA and the OccuSystems
Board and the CRA Board have certain interests in the Mergers that are different
from, or in addition to, the interests of stockholders of OccuSystems and CRA
generally.
 
    OCCUSYSTEMS
 
    DIRECTORS AND EXECUTIVE OFFICERS OF CONCENTRA.  John K. Carlyle, Robert W.
O'Leary, Robert A. Ortenzio and Paul B. Queally, each of whom is a current
director of OccuSystems, will become directors of Concentra. In addition,
certain executive officers of OccuSystems, including John K. Carlyle, Daniel J.
Thomas, Richard A. Parr II, W. Thomas Fogarty, M.D. and James M. Greenwood, are
executive officers (or, in the case of Mr. Carlyle, Chairman) of Concentra and
parties to employment agreements with Concentra that become effective upon
consummation of the Mergers. In addition, Dr. Richard D. Rehm, a director of
OccuSystems, has entered into an agreement to terminate his existing employment
agreement upon effectiveness of the Mergers in consideration of the payment by
OccuSystems to Dr. Rehm of a $74,000 lump sum amount. See "MANAGEMENT OF
CONCENTRA."
 
    STOCK OPTION PROGRAMS.  At the Effective Time, each outstanding OccuSystems
Option shall be converted into an option to purchase shares of Concentra Common
Stock, as provided below. Following the Effective Time, each such OccuSystems
Option will be exercisable for the same number of shares, and at the same
exercise price, as are in effect for such OccuSystems Option at the Effective
Time. As of March 31, 1997, directors and executive officers of OccuSystems held
outstanding OccuSystems Options to purchase 1,292,800 shares of OccuSystems
Common Stock at exercise prices ranging from $3.00 to $25.88 per share.
Consummation of the Mergers will constitute a "change in control" under certain
OccuSystems Options held by OccuSystems' directors and executive officers; as a
result, OccuSystems Options to purchase 387,075 shares of OccuSystems Common
Stock that would not otherwise vest and become exercisable until certain dates
after the Effective Time will, by virtue of consummation of the Mergers, vest
and become exercisable as of the Effective Time.
 
    EMPLOYEE BENEFIT PLANS.  The Reorganization Agreement provides that,
immediately following the Effective Time, Concentra will cause employee benefit
plans to be in effect for the benefit of OccuSystems' employees that are
reasonably comparable in the aggregate to the employee benefit plans that were
in effect prior to the Effective Time.
 
                                       35
<PAGE>
    CRA
 
    DIRECTORS AND EXECUTIVE OFFICERS OF CONCENTRA.  Following the Mergers,
Donald J. Larson, Lois E. Silverman, George H. Conrades and Mitchell T. Rabkin,
M.D., each of whom is a current director of CRA, will become members of the
Concentra Board of Directors. In addition, certain executive officers of CRA,
including Donald J. Larson, John A. McCarthy, Jr., Joseph F. Pesce and Peter R.
Gates, are executive officers of Concentra and parties to employment agreements
with Concentra that become effective upon consummation of the Mergers. In
addition, Ms. Lois E. Silverman, CRA's Chairman, has entered into an agreement
to terminate her existing employment agreement upon effectiveness of the Mergers
in consideration of the payment by CRA of a $300,000 lump sum amount. See
"MANAGEMENT OF CONCENTRA."
 
    STOCK OPTION PROGRAMS.  The Reorganization Agreement provides that, at the
Effective Time, each outstanding option or right to purchase shares of CRA
Common Stock (a "CRA Option") shall be converted into an option to purchase
shares of Concentra Common Stock. Following the Effective Time, each such CRA
Option will be exercisable upon the same terms and conditions as are in effect
for such CRA Option at the Effective Time, except that (i) each such CRA Option
will be exercisable for that number of shares of Concentra Common Stock equal to
the product of (x) the number of shares of CRA Common Stock for which such CRA
Option was exercisable and (y) the CRA Ratio and (ii) the exercise price of such
CRA Option will be equal to the exercise price of such option as of the date of
the Reorganization Agreement divided by the CRA Ratio. As of March 31, 1997,
directors and executive officers of CRA held outstanding CRA Options to purchase
434,320 shares of CRA Common Stock at exercise prices ranging from $5.89 to
$49.25 per share. Consummation of the Mergers will not accelerate the vesting or
exercisability of any of the CRA Options.
 
    EMPLOYEE BENEFIT PLANS.  The Reorganization Agreement provides that,
immediately following the Effective Time, Concentra will cause employee benefit
plans to be in effect for the benefit of CRA's employees that are reasonably
comparable in the aggregate to the employee benefit plans that were in effect
prior to the Effective Time.
 
    CONCENTRA
 
    INDEMNIFICATION; DIRECTORS' AND OFFICERS' LIABILITY INSURANCE.  The
Reorganization Agreement provides that, from and after the Effective Time,
Concentra will indemnify, defend and hold harmless to the fullest extent that
OccuSystems or CRA would have been permitted under applicable law each person
who is now, or has been at any time prior to the date hereof, an officer or
director of OccuSystems or CRA (individually an "Indemnified Party" and
collectively the "Indemnified Parties"), against all losses, claims, damages,
liabilities, costs or expenses (including attorneys' fees), judgments, fines,
penalties and amounts paid in settlement in connection with any claim, action,
suit, proceeding or investigation arising out of or pertaining to acts or
omissions, or alleged acts or omissions, by them in their capacities as such
occurring at or prior to the Effective Time. The Reorganization Agreement also
provides that Concentra will maintain, and cause OccuSystems and CRA to keep in
effect, provisions of their charter and bylaws providing for exculpation of
director and officer liability and indemnification of the Indemnified Parties to
the fullest extent permitted under applicable law, which provisions shall not be
amended except as required by applicable law or except to make changes permitted
by law that would enlarge the Indemnified Parties' rights of exculpation and
indemnification. The Reorganization Agreement also provides that, for period of
six years after the Effective Time, directors' and officers' liability insurance
will be maintained covering the Indemnified Parties who are currently covered,
in their capacities as directors and officers, by OccuSystems' and CRA's
existing directors' and officers' liability insurance policies on terms no less
advantageous to the Indemnified Parties than such existing insurance to the
extent such coverage can be maintained or procured by the payment of an annual
premium not exceeding one and one-half times the current annual
 
                                       36
<PAGE>
premium paid by OccuSystems for its existing coverage (which current annual
premium is approximately $110,000).
 
    EMPLOYMENT AGREEMENTS.  Concentra has entered into employment agreements
with its Chairman and each of its executive officers. The employment agreements
provide for base salaries as follows: Mr. Carlyle, $340,000; Mr. Larson,
$350,000; Mr. McCarthy, $260,000; Mr. Parr, $230,000; Mr. Pesce, $260,000; Mr.
Thomas, $260,000; Dr. Fogarty, $240,000; Mr. Gates, $230,000; and Mr. Greenwood,
$230,000 (each being an "Officer"). Each of the employment agreements also
provide that bonuses, if any, will be paid at the discretion of Concentra's
Board of Directors and allows participation in any employee benefit plan adopted
by Concentra for its employees. The term of each of the agreements is two years.
Each of the agreements entitles each such individual to receive severance
payments if Concentra (i) terminates the employment agreement without Cause (as
defined in the employment agreement), (ii) the Officer terminates the agreement
for Good Reason (as defined in the employment agreement, which, for Mr. Carlyle,
includes ceasing to be Chairman of the Board of Concentra for any reason) or
(iii) Concentra does not renew the employment agreement other than because of
death or disability of the Officer. Such severance payments shall equal two
years' base salary for Messrs. Carlyle and Larson and one year's base salary for
each of the other Officers. In addition, restricted stock and stock options to
purchase an aggregate of 330,000 shares granted by OccuSystems to Messrs.
Carlyle, Thomas, Parr, Fogarty and Greenwood will accelerate upon termination of
such Officers by Concentra without Cause or by such Officers for Good Reason.
 
    REGISTRATION RIGHTS AGREEMENT.  Lois E. Silverman, Chairman of the Board of
CRA, Donald J. Larson, President and Chief Executive Officer of CRA, and CRA are
parties to a Registration Rights Agreement dated March 8, 1994 (the
"Registration Rights Agreement"). Pursuant to the Registration Rights Agreement,
Ms. Silverman and Mr. Larson were granted the right to require CRA to file up to
three registration statements under the Securities Act on their behalf. CRA also
granted Ms. Silverman and Mr. Larson the right to register the sale of their
shares on any registration statement (except one on Form S-4 or S-8 or any
successor thereto) filed by CRA, subject to certain limitations. Concentra has
agreed to enter into an Agreement of Acceptance pursuant to which Concentra will
assume the obligations of CRA under the Registration Rights Agreement and will
grant Lois E. Silverman and Donald J. Larson the right to register shares of
Concentra Common Stock on the same terms as in the Registration Rights
Agreement.
 
ACCOUNTING TREATMENT
 
    OccuSystems and CRA have received a "pooling letter" from Arthur Andersen
LLP, their independent public accountants, dated April 21, 1997, to the effect
that the Mergers will be treated as a pooling-of-interests for accounting
purposes. Under this method of accounting, the assets and liabilities of
OccuSystems and CRA will be combined based on the respective carrying values of
the accounts in the historical financial statements of each entity. Results of
operations of the combined company will include income of OccuSystems and CRA
for the entire fiscal period in which the combination occurs and the historical
results of operations of the separate companies for fiscal years prior to the
Mergers will be combined and reported as the results of operations of the
combined company.
 
    Consummation of the Mergers is conditioned upon OccuSystems and CRA
receiving an opinion, dated the Closing Date of the Mergers, to the effect that
the business combination to be effected by the Mergers would be properly
accounted for as a pooling of interests for accounting purposes. See "THE
REORGANIZATION AGREEMENT -- Conditions to the Mergers." Certain events,
including certain transactions with respect to OccuSystems Common Stock or CRA
Common Stock by affiliates of OccuSystems or CRA, respectively, may prevent the
Mergers from qualifying as a pooling of interests for accounting purposes. See
"THE MERGERS -- Resale Restrictions."
 
                                       37
<PAGE>
OCCUSYSTEMS NOTES
 
    Contemporaneously with the Mergers, Concentra will assume an aggregate
principal amount of $97,750,000 of OccuSystems's outstanding 6% Convertible
Subordinated Notes due 2001 (the "OccuSystems Notes"). The OccuSystems Notes are
currently convertible into OccuSystems Common Stock and, subsequent to the
Mergers, the OccuSystems Notes will be convertible into 3,291,246 shares of
Concentra Common Stock, subject to adjustment in certain events. Consummation of
the Mergers will not constitute a change in control under the Indenture
governing the OccuSystems Notes. After the Mergers, the OccuSystems Notes will
be unsecured general obligations of Concentra, subordinated in right of payment
to all existing and future Senior Indebtedness (as defined in such indenture) of
Concentra. See "DESCRIPTION OF CONCENTRA CAPITAL STOCK -- Convertible
Subordinated Notes."
 
CERTAIN FEDERAL INCOME TAX CONSEQUENCES
 
    The following is a summary of the material federal income tax consequences
of the Mergers and the tax opinions to be received by OccuSystems and CRA and is
based upon current provisions of the Code, existing regulations thereunder and
current administrative rulings and court decisions, all of which are subject to
change. No attempt has been made to comment on all federal income tax
consequences of the Mergers that may be relevant to particular holders,
including holders that are subject to special tax rules such as dealers in
securities, foreign persons, mutual funds, insurance companies, tax-exempt
entities and holders who do not hold their shares as capital assets. Holders of
OccuSystems Common Stock and CRA Common Stock are advised and expected to
consult their own tax advisers regarding the federal income tax consequences of
the Mergers in light of their personal circumstances and the consequences under
state, local and foreign tax laws.
 
    No ruling from the Internal Revenue Service ("IRS") has been or will be
requested in connection with the Mergers. The respective obligations of
OccuSystems and CRA to consummate the Mergers are conditioned upon the receipt
of opinions of their respective special counsel, Vinson & Elkins, L.L.P. and
Hutchins, Wheeler & Dittmar, a Professional Corporation, that the OccuSystems
Merger will be treated for federal income tax purposes as a reorganization
within the meaning of Section 368(a) of the Code and the CRA Merger will be
treated for federal income tax purposes as a reorganization within the meaning
of Section 368(a) of the Code and/or transfer of property to Concentra by the
holders of CRA Common Stock governed by Section 351 of the Code. See "THE
REORGANIZATION AGREEMENT -- Conditions to the Mergers." Such opinions will be
subject to certain assumptions and based on certain representations of
OccuSystems and CRA, including representations that the historic stockholders of
OccuSystems and CRA will retain a significant continuing equity interest in
Concentra and that substantially all of the assets of OccuSystems and CRA will
be retained by Concentra. Stockholders of OccuSystems and CRA should be aware
that such opinions are not binding on the IRS and no assurance can be given that
the IRS will not adopt a contrary position or that the IRS position would not be
sustained by a court.
 
    The following federal income tax consequences will occur upon a
reorganization under Section 368(a) of the Code:
 
        (a) no gain or loss will be recognized by OccuSystems, CRA or Concentra
    in connection with the Mergers;
 
        (b) no gain or loss will be recognized by a holder of OccuSystems Common
    Stock upon the exchange of all of such holder's shares of OccuSystems Common
    Stock or CRA Common Stock solely for shares of Concentra Common Stock in the
    Mergers;
 
        (c) the aggregate basis of the shares of Concentra Common Stock received
    by an OccuSystems or CRA stockholder in the Mergers (including any
    fractional share deemed received) will be the same
 
                                       38
<PAGE>
    as the aggregate basis of the shares of OccuSystems Common Stock or CRA
    Common Stock surrendered in exchange therefor;
 
        (d) the holding period of the shares of Concentra Common Stock received
    by an OccuSystems or CRA stockholder in the Mergers will include the holding
    period of the shares of OccuSystems Common Stock or CRA Common Stock
    surrendered in exchange therefor, provided that such shares of OccuSystems
    Common Stock or CRA Common Stock are held as capital assets at the Effective
    Time;
 
        (e) a stockholder of CRA who receives cash in lieu of a fractional share
    will recognize gain or loss equal to the difference, if any, between such
    stockholder's basis in the fractional share (as described in paragraph (c)
    above) and the amount of cash received. Such gain or loss will be a capital
    gain or loss if the CRA Common Stock is held by such stockholder as a
    capital asset at the Effective Time; and
 
        (f) a stockholder of CRA who exercises dissenters' rights will recognize
    gain or loss equal to the difference, if any, between such stockholder's
    basis in the shares of CRA Common Stock sold pursuant to the exercise of
    dissenters' rights and the amount of cash received. Such gain or loss will
    be a capital gain or loss if the CRA Common Stock is held by such
    stockholder as a capital asset at the time of sale.
 
    THIS FEDERAL INCOME TAX DISCUSSION IS FOR GENERAL INFORMATION ONLY AND MAY
NOT APPLY TO ALL HOLDERS OF OCCUSYSTEMS COMMON STOCK OR TO ALL HOLDERS OF CRA
COMMON STOCK. SUCH HOLDERS ARE URGED TO CONSULT THEIR OWN TAX ADVISORS AS TO THE
SPECIFIC TAX CONSEQUENCES OF THE MERGERS.
 
REGULATORY APPROVALS
 
    Under the HSR Act and the rules promulgated thereunder by the FTC, the
Mergers may not be consummated until notifications have been given and certain
information has been furnished to the Antitrust Division of the United States
Department of Justice and the FTC and specified waiting period requirements have
been satisfied. OccuSystems and CRA each filed with the Antitrust Division and
the FTC a Notification and Report Form (the "Notification and Report Form") with
respect to the Mergers on May 13, 1997. The initial waiting period for each of
these filings was scheduled to expire at 11:59 p.m. on June 12, 1997.
 
    The Antitrust Division and the FTC frequently scrutinize the legality under
the antitrust laws of transactions such as the Mergers. At any time before or
after the Special Meetings, the Antitrust Division or the FTC could take such
action under the antitrust laws as it deems necessary or desirable in the public
interest, including seeking to enjoin the Mergers or seeking the divestiture of
substantial assets of CRA or it subsidiaries or OccuSystems or its subsidiaries.
 
    In addition, state antitrust authorities may also bring legal action under
the antitrust laws. Such action could include seeking to enjoin the consummation
of the Mergers or seeking divesture of certain assets of OccuSystems or CRA.
Private parties may also seek to take legal action under the antitrust laws
under certain circumstances. There can be no assurance that a challenge to the
Mergers on antitrust grounds will not be made or, if such a challenge is made,
of the result thereof.
 
    CRA's business is regulated primarily at the state level, and it must comply
with regulatory requirements which differ from state to state. CRA and CRA
subsidiaries hold numerous licenses, certifications, permits and/or other
approvals (collectively "Approvals") issued by regulatory agencies in various
states in which CRA and its subsidiaries do business in compliance with
applicable state laws. The business activities for which Approvals have been
issued fall into three general categories: (i) Approvals for workers'
compensation managed care programs; (ii) Approvals for medical review services;
and (iii) Approvals for provider networks.
 
                                       39
<PAGE>
    Most of the regulatory agencies which have issued Approvals to CRA or CRA
subsidiaries in connection with their business as now conducted will require
notification of the CRA Merger and the other transactions contemplated by the
Reorganization Agreement. The precise nature of the required notification varies
by state and regulatory agency. In almost all instances, notification to state
regulatory agencies may be made by letter, with documentation attached as
necessary, after the Mergers are completed. With respect to several of the
Approvals, the state regulatory agencies may require CRA to file a new or
amended application subsequent to the notification.
 
QUOTATION OF CONCENTRA COMMON STOCK
 
    Concentra intends to apply for the quotation of the Concentra Common Stock
on the Nasdaq National Market under the symbol "CCMC." It is a condition to
OccuSystems' and CRA's obligations to consummate the Mergers that the shares of
Concentra Common Stock to be issued to the stockholders of OccuSystems and CRA
in connection with the Mergers shall have been approved for quotation on the
Nasdaq National Market, subject only to official notice of issuance.
 
RESALE RESTRICTIONS
 
    All shares of Concentra Common Stock received by OccuSystems and CRA
stockholders in the Mergers will be freely transferable, except that shares of
Concentra Common Stock received by persons who are deemed to be "affiliates" (as
such term is defined under the Securities Act) of OccuSystems or CRA prior to
the Mergers may be resold by them only in transactions permitted by the resale
provisions of Rule 145 promulgated under the Securities Act (or Rule 144 in the
case of such persons who become affiliates of Concentra) or as otherwise
permitted under the Securities Act. Persons who may be deemed to be affiliates
of OccuSystems, CRA or Concentra generally include individuals or entities that
control, are controlled by, or are under common control with, such party and may
include certain officers and directors of such party as well as principal
stockholders of such party. The Reorganization Agreement requires OccuSystems
and CRA to use reasonable efforts to deliver or cause to be delivered to
Concentra, prior to the Closing Date, from each affiliate thereof, a letter
agreement to the effect that such person will not (i) offer or sell or otherwise
dispose of any of the shares of Concentra Common Stock issued to such persons in
or pursuant to the Mergers in violation of the Securities Act or the rules and
regulations promulgated by the Commission thereunder, (ii) sell or transfer any
stock of CRA or OccuSystems 30 days prior to consummation of the Mergers or
(iii) sell, transfer or otherwise dispose of any Concentra Common Stock until
Concentra publishes results covering at least 30 days of combined operations of
Concentra, OccuSystems and CRA (an "Affiliate Letter"). Further, the
Reorganization Agreement prohibits the issuance of Concentra Common Stock to an
affiliate of OccuSystems or CRA prior to such affiliate executing an Affiliate
Letter.
 
DISSENTERS' RIGHTS
 
    Under the DGCL, holders of OccuSystems Common Stock are not entitled to
dissenters' rights in connection with the OccuSystems Merger because the
OccuSystems Common Stock is designated as a national market system security on
an interdealer quotation system by the National Association of Securities
Dealers, Inc. Under the MBCL, holders of CRA Common Stock who comply with
sections 86 through 88 of the MBCL have appraisal rights.
 
    Under the MBCL, CRA stockholders will have certain dissenters' rights of
appraisal. If the CRA Proposal is approved by the CRA stockholders at the CRA
Meeting and the CRA Merger is effected by CRA, any stockholder (1) who files
with the corporation before the taking of the vote on the CRA Proposal, written
objection to the proposed action stating that such stockholder intends to demand
payment for such stockholder's shares if the action is taken and (2) whose
shares are not voted in favor of such action has or may have the right to demand
in writing from CRA, within 20 days after the date of mailing to such
stockholder of notice in writing that the corporate action has become effective,
payment
 
                                       40
<PAGE>
for such stockholder's shares and an appraisal of the value thereof. CRA and any
such stockholder shall in such case have the rights and duties and shall follow
the procedure set forth in sections 88 to 98, inclusive, of the MBCL. Failure to
vote against the CRA Proposal will constitute a waiver of such rights set forth
in Appendix I. Except as set forth herein, stockholders of CRA will not be
entitled to appraisal rights in connection with the CRA Merger.
 
    Within ten days after the date on which the CRA Merger becomes effective,
CRA must notify each stockholder who, in compliance with the requirements
described above, filed written objection and did not vote any shares in favor of
such action, that the action approved at the meeting of CRA has become
effective. If within 20 days after the date of mailing of this notice, any
stockholder to whom CRA is required to give such notice demands in writing from
CRA payments for such stockholder's stock, CRA will pay to such stockholder the
fair value of the stock within 30 days after the expiration of the period during
which such demand may be made. If during this 30 day period CRA and any such
objecting stockholder fail to agree as to the value of such stock, CRA, or any
such stockholder, may within four months after the expiration of such 30 day
period demand a determination of the value of the stock of all such objecting
stockholders by a bill in equity filed in the superior court in the county where
CRA has its principal office in Massachusetts.
 
    The foregoing is only a partial summary of sections 88 to 98, inclusive, of
the MBCL, and is qualified in its entirety by reference to the provisions
thereof, the full text of which is set forth as Appendix I to this Joint Proxy
Statement/Prospectus. Each stockholder of CRA is urged to read carefully the
full text of sections 88 to 98, inclusive, of the MBCL.
 
                          THE REORGANIZATION AGREEMENT
 
    The following is a brief summary of the material provisions of the
Reorganization Agreement, a copy of which is attached as Appendix A to this
Joint Proxy Statement/Prospectus and is incorporated herein by reference. This
summary is qualified in its entirety by reference to the full and complete text
of the Reorganization Agreement.
 
THE MERGERS
 
    Pursuant to the Reorganization Agreement and subject to the terms and
conditions thereof, OccuSystems will be merged with and into Concentra and a
wholly-owned subsidiary of Concentra will be merged with and into CRA. As a
result of the Mergers, CRA will become a wholly owned subsidiary of Concentra.
As part of the Mergers, stockholders of OccuSystems and CRA will receive the
consideration described below.
 
    Subject to the terms and conditions of the Reorganization Agreement, the
closing of the transactions contemplated thereby will take place on the third
business day following the day on which all conditions to the Reorganization
Agreement are satisfied or waived (the "Closing Date"). The Mergers will become
effective upon both the filing of a certificate of merger with the Secretary of
State of the State of Delaware with respect to the OccuSystems Merger and the
filing of articles of merger with the Secretary of State of the Commonwealth of
Massachusetts relating to the CRA Merger. The time at which the Mergers become
effective is referred to as the Effective Time.
 
CONVERSION OF OCCUSYSTEMS COMMON STOCK
 
    Pursuant to the Reorganization Agreement, upon consummation of the
OccuSystems Merger, (i) each share of OccuSystems Common Stock, except for
OccuSystems Treasury Stock, issued and outstanding at the Effective Time, will
be converted into one share of Concentra Common Stock and upon such conversion
all shares of OccuSystems Common Stock will be canceled and cease to exist, and
(ii) all shares of OccuSystems Treasury Stock will be canceled and retired
without payment of any consideration therefor.
 
                                       41
<PAGE>
    HOLDERS OF OCCUSYSTEMS COMMON STOCK SHOULD NOT SEND ANY CERTIFICATES
REPRESENTING OCCUSYSTEMS COMMON STOCK WITH THE ENCLOSED PROXY CARD. IF THE
MERGERS ARE APPROVED, A LETTER OF TRANSMITTAL WILL BE MAILED AFTER THE EFFECTIVE
TIME TO EACH PERSON WHO WAS A HOLDER OF OUTSTANDING SHARES OF OCCUSYSTEMS COMMON
STOCK IMMEDIATELY PRIOR TO THE EFFECTIVE TIME. OCCUSYSTEMS STOCKHOLDERS SHOULD
SEND CERTIFICATES REPRESENTING OCCUSYSTEMS COMMON STOCK TO THE EXCHANGE AGENT
ONLY AFTER THEY RECEIVE, AND IN ACCORDANCE WITH, THE INSTRUCTIONS CONTAINED IN
THE LETTER OF TRANSMITTAL.
 
    OCCUSYSTEMS STOCK OPTIONS.  As provided in the Reorganization Agreement, at
the Effective Time, each OccuSystems Option will be assumed by Concentra and
converted into an option to purchase Concentra Common Stock. Following the
Effective Time, each such OccuSystems Option will be exercisable for the same
number of shares, and at the same exercise price, as in effect for such
OccuSystems Option. See "THE MERGERS -- Interests of Certain Persons in the
Mergers -- OccuSystems -- Stock Option Programs."
 
    DIVIDENDS.  No dividends or other distributions declared after the Effective
Time on Concentra Common Stock shall be paid with respect to any shares of
OccuSystems Common Stock represented by an OccuSystems stock certificate
("OccuSystems Certificate") until such OccuSystems Certificate is surrendered
for exchange according to the procedures described above.
 
    FRACTIONAL SHARES.  Because the OccuSystems Ratio equals one, no fractional
shares of Concentra Common Stock will be issued to any stockholder of
OccuSystems upon consummation of the Mergers.
 
CONVERSION OF CRA COMMON STOCK
 
    Pursuant to the Reorganization Agreement, upon consummation of the CRA
Merger, (i) each share of CRA Common Stock issued and outstanding immediately
prior to the Effective Time, except for CRA Treasury Stock or Dissenting Shares,
will be converted into the right to receive 1.786 shares of Concentra Common
Stock and upon such conversion such shares of CRA Common Stock will be canceled
and cease to exist, and (ii) all CRA Treasury Stock, if any, will be canceled
and retired without payment of any consideration therefor.
 
    HOLDERS OF CRA COMMON STOCK SHOULD NOT SEND ANY CERTIFICATES REPRESENTING
CRA COMMON STOCK WITH THE ENCLOSED PROXY CARD. IF THE MERGERS ARE APPROVED, A
LETTER OF TRANSMITTAL WILL BE MAILED AFTER THE EFFECTIVE TIME TO EACH PERSON WHO
WAS A HOLDER OF OUTSTANDING SHARES OF CRA COMMON STOCK IMMEDIATELY PRIOR TO THE
EFFECTIVE TIME. CRA STOCKHOLDERS SHOULD SEND CERTIFICATES REPRESENTING CRA
COMMON STOCK TO THE EXCHANGE AGENT ONLY AFTER THEY RECEIVE, AND IN ACCORDANCE
WITH, THE INSTRUCTIONS CONTAINED IN THE LETTER OF TRANSMITTAL.
 
    CRA OPTIONS.  As provided in the Reorganization Agreement, at the Effective
Time, each CRA Option will be assumed by Concentra and converted into an option
to purchase Concentra Common Stock. Following the Effective Time, each such CRA
Option will be exercisable on the same terms and conditions as are then
applicable to such CRA Option, except that (i) each such CRA Option will be
exercisable for a number of shares of Concentra Common Stock equal to the
product of (x) the number of shares of CRA Common Stock for which such CRA
Option was exercisable and (y) the CRA Ratio and (ii) the exercise price of such
CRA Option will be equal to the exercise price of such CRA Option as of the date
of the Reorganization Agreement, divided by the CRA Ratio. See "THE MERGERS --
Interests of Certain Persons in the Mergers -- CRA -- Stock Option Programs."
 
    DIVIDENDS.  No dividends or other distributions declared after the Effective
Time on Concentra Common Stock shall be paid with respect to any shares of CRA
Common Stock represented by a CRA
 
                                       42
<PAGE>
stock certificate ("CRA Certificate") until such CRA Certificate is surrendered
for exchange according to the procedures described above.
 
    FRACTIONAL SHARES.  No fractional shares of Concentra Common Stock shall be
issued to any stockholder of CRA upon consummation of the Mergers. For each
fractional share that would otherwise be issued, Concentra will pay by check an
amount equal to a pro rata portion of the net proceeds of the sale by the
Exchange Agent of shares of Concentra Common Stock, representing the aggregate
of all such fractional shares, and the aggregate dividends or other
distributions that are payable with respect to such shares of Concentra Common
Stock. Such sales are to be executed by the Exchange Agent as soon as
practicable after the Effective Time at then prevailing prices on the Nasdaq
National Market.
 
CERTAIN REPRESENTATIONS AND WARRANTIES
 
    The Reorganization Agreement contains customary representations and
warranties by both OccuSystems and CRA as to, among other things, (i) existence,
good standing and corporate authority to enter into the Reorganization Agreement
and related agreements, (ii) authorization, validity and effect of the
Reorganization Agreement and related agreements, (iii) capitalization, (iv)
ownership of subsidiaries, (v) the lack of certain investments or interests,
(vi) the compliance of the Mergers with charters, bylaws and the law, (vii) the
absence of certain material defaults or violations, (viii) the filing of all
required documents with the Commission and the accuracy of financial statements
filed therewith, (ix) material litigation, (x) material adverse changes in each
party's business, results of operations, financial condition or prospects, (xi)
tax matters, (xii) employee benefit plans, (xiii) labor matters, (xiv) brokers,
(xv) fairness opinions and (xvi) pooling accounting treatment.
 
CERTAIN COVENANTS
 
    CONDUCT OF BUSINESS PENDING THE MERGERS.  Pursuant to the Reorganization
Agreement, OccuSystems and CRA have made various customary covenants. CRA has
agreed that, prior to the Effective Time, CRA and its significant subsidiaries
will conduct their operations according to their usual, regular and ordinary
course of business. Specifically, CRA has agreed, among other things, (i) to
preserve intact its business organization, relationships and goodwill and to
keep available the services of its officers and employees, (ii) not to amend its
certificate of incorporation or bylaws (other than bylaw amendments that are not
material to CRA or to the consummation of the Mergers), (iii) to promptly notify
OccuSystems of any breach of any representation or warranty or any CRA Material
Adverse Effect (as defined in the Reorganization Agreement), (iv) not to (A)
except pursuant to the exercise of options, warrants, conversion rights and
other contractual rights existing on the date of the Reorganization Agreement
and disclosed to OccuSystems, issue any of its capital stock, effect a stock
split or otherwise change its capitalization from that existing on the date of
the Reorganization Agreement, (B) grant, confer or award any option, warrant,
conversion right or other right not existing on the date of the Reorganization
Agreement to acquire any shares of its capital stock (other than the grant of
options to acquire up to 15,000 shares of CRA Common Stock pursuant to the terms
of the CRA's stock option plans at an exercise price of not less than the fair
market value of the CRA Common Stock on the date of grant) or grant, confer or
award any bonuses or other forms of cash incentives to any officer, director or
employee except consistent with past practice, (C) increase any compensation of
its present or future, officers, directors or employees, except for normal
increases consistent with past practice or as required under the written terms
of an employment agreement in effect on or before December 31, 1996, enter into
any employment agreement with any present or future employee, officer or
director or amend any such agreement in any material respect, grant any
severance or termination pay to any officer, director or employee other than
pursuant to existing severance arrangements and policies, or adopt any new
benefit plan (including any stock option, stock benefit or stock purchase plan)
or amend any existing benefit plan in any material respect, (v) not to (A)
declare any dividends, or make any distributions with respect to its capital
stock, (B) redeem or otherwise acquire any of its capital stock or stock of its
subsidiaries, or (C) split, combine or
 
                                       43
<PAGE>
reclassify any of its capital stock or issue or authorize or propose the
issuance of any other securities in respect of, in lieu of or in substitution of
its capital stock, (vi) not to dispose of any of its assets, except in the
ordinary course of business, or acquire any business or assets except as
previously disclosed to OccuSystems and acquisitions involving the payment of
consideration by CRA not in excess of $10 million for any single transaction or
$25 million in the aggregate, (vii) not to incur material indebtedness for
borrowed money, or make any loans, advances or capital contributions to, or
investments (other than non-controlling investments in the ordinary course of
business or other investments permitted pursuant to clause (vi) above) in, any
other person other than a wholly-owned subsidiary, or issue or sell any debt
securities, other than borrowings under existing lines of credit in the ordinary
course of business, in each case, in an amount exceeding $1,000,000, (viii) not,
except as previously approved by the CRA Board and identified to OccuSystems
prior to the date the Reorganization Agreement, or except in the ordinary course
of business, to make or commit to make capital expenditures other than (A)
capital expenditures budgeted for the fiscal year ending December 31, 1997, and
(B) capital expenditures (not otherwise included in budgeted capital
expenditures referred to in clause (A) above) that may be made by CRA in
connection with the acquisitions by CRA or its subsidiaries permitted under
clause (vi) above, (ix) not to mortgage or otherwise encumber or subject to any
lien any properties or assets except as would not be reasonably likely to have a
material adverse effect on CRA, (x) not to make any change to its accounting
(including tax accounting) methods, principles or practices, except as may be
required by generally accepted accounting principles and except, in the case of
tax accounting methods, principles or practices, in the ordinary course of
business of CRA, (xi) not to permit any of its subsidiaries to enter into any
agreement or arrangement with any of their respective affiliates, other than
with wholly-owned subsidiaries of CRA, on terms less favorable to CRA or such
subsidiary, as the case may be, than could be reasonably expected to have been
obtained with an unaffiliated third party on an arm's-length basis, (xii) to use
commercially reasonable efforts to maintain with financially responsible
companies insurance in such amounts and against such risks and losses as are
customary for companies engaged in their respective businesses, and (xiii) not
to (A) make or rescind any material express or deemed election relating to
taxes, unless it is reasonably expected that such action will not result in a
material adverse effect on CRA, (B) settle or compromise any material claim,
action, suit, litigation, proceeding, arbitration, investigation, audit or
controversy relating to taxes, except where such settlement or compromise will
not result in an material adverse effect on CRA, or (C) change in any material
respect any of its methods of reporting income or deductions for federal income
tax purposes from those employed in the preparation of its federal income tax
returns that have been filed for prior taxable years, except as may be required
by applicable law or except for changes that are reasonably expected not to
result in a material adverse effect on CRA.
 
    OccuSystems has agreed that, prior to the Effective Time, OccuSystems and
its significant subsidiaries will conduct their operations according to their
usual, regular and ordinary course of business. OccuSystems has agreed, among
other things, (i) to preserve intact its business organization, relationships
and goodwill and to keep available the services of its officers and employees,
(ii) not to amend its certificate of incorporation or bylaws (other than bylaw
amendments that are not material to OccuSystems or to the consummation of the
Mergers), (iii) to promptly notify CRA of any breach of any representation or
warranty or any OccuSystems Material Adverse Effect (as defined in the
Reorganization Agreement), (iv) not to (A) except pursuant to the exercise of
options, warrants, conversion rights and other contractual rights existing on
the date of the Reorganization Agreement and disclosed to CRA, issue any of its
capital stock, effect a stock split or otherwise change its capitalization from
that existing on the date of the Reorganization Agreement, (B) confer or award
any option, warrant, conversion right or other right not existing on the date of
the Reorganization Agreement to acquire any shares of its capital stock (other
than the grant of options to acquire up to 15,000 shares of OccuSystems Common
Stock pursuant to the terms of the OccuSystems' stock option plans at an
exercise price of not less than the fair market value of the OccuSystems Common
Stock on the date of grant) or grant, confer or award any bonuses or other forms
of cash incentives to any officer, director or employee except consistent with
past practice, (C) increase any
 
                                       44
<PAGE>
compensation of its present or future officers, directors or employees, except
for normal increases consistent with past practice or as required under the
written terms of an employment agreement in effect on or before December 31,
1996; enter into any employment agreement with any present or future employee,
officer or director, or amend any such agreement in any material respect, grant
any severance or termination pay to any officer, director or employee other than
pursuant to existing severance arrangements and policies, or adopt any new
benefit plan (including any stock option, stock benefit or stock purchase plan)
or amend any existing benefit plan in any material respect, (v) not to (A)
declare any dividends, or make any distributions with respect to its capital
stock, (B) redeem any of its capital stock or stock of its subsidiaries; or (C)
split, combine or reclassify any of its capital stock or issue or authorize or
propose the issuance of any other securities in respect of, in lieu of or in
substitution of its capital stock, (vi) not to dispose of any of its assets,
except in the ordinary course of business, or acquire any business or assets
except as previously disclosed to CRA and acquisitions involving the payment of
consideration by OccuSystems not in excess of $10 million for any single
transaction or $25 million in the aggregate, (vii) not to incur material
indebtedness for borrowed money, or make any loans, advances or capital
contributions to, or investments (other than non-controlling investments in the
ordinary course of business or other investments permitted pursuant to clause
(vi) above) in, any other person other than a wholly-owned subsidiary, or issue
or sell any debt securities, other than borrowings under existing lines of
credit in the ordinary course of business, in each case, in an amount exceeding
$1,000,000, (viii) not, except as previously approved by the OccuSystems Board
and identified to CRA prior to the date the Reorganization Agreement, or except
in the ordinary course of business, to make or commit to make capital
expenditures other than (A) capital expenditures budgeted for the fiscal year
ending December 31, 1997, and (B) capital expenditures (not otherwise included
in budgeted capital expenditures referred to in clause (A) above) that may be
made by OccuSystems in connection with the acquisitions by OccuSystems or its
subsidiaries permitted under clause (vi) above, (ix) not to mortgage or
otherwise encumber or subject to any lien any properties or assets except as
would not be reasonably likely to have a material adverse effect on OccuSystems,
(x) not to make any change to its accounting (including tax accounting) methods,
principles or practices, except as may be required by generally accepted
accounting principles and except, in the case of tax accounting methods,
principles or practices, in the ordinary course of business of OccuSystems, (xi)
not to permit any of its subsidiaries to enter into any agreement or arrangement
with any of their respective affiliates, other than with wholly-owned
subsidiaries of OccuSystems, on terms less favorable to OccuSystems or such
subsidiary, as the case may be, than could be reasonably expected to have been
obtained with an unaffiliated third party on an arm's-length basis, (xii) to use
commercially reasonable efforts to maintain with financially responsible
companies insurance in such amounts and against such risks and losses as are
customary for companies engaged in their respective businesses, and (xiii) not
to (A) make or rescind any material express or deemed election relating to
taxes, unless it is reasonably expected that such action will not result in a
material adverse effect on OccuSystems, (B) settle or compromise any material
claim, action, suit, litigation, proceeding, arbitration, investigation, audit
or controversy relating to taxes, except where such settlement or compromise
will not result in an material adverse effect on OccuSystems, or (C) change in
any material respect any of its methods of reporting income or deductions for
federal income tax purposes from those employed in the preparation of its
federal income tax returns that have been filed for prior taxable years, except
as may be required by applicable law or except for changes that are reasonably
expected not to result in a material adverse effect on OccuSystems.
 
    CRA ALTERNATIVE PROPOSALS.  Pursuant to the Reorganization Agreement, CRA
has agreed that it will not, and will not authorize or (to the extent within its
control) permit any of its officers, directors, employees, agents, affiliates
and other representatives or those of any of its subsidiaries to, directly or
indirectly, solicit or encourage (including by way of providing information) any
prospective acquiror or the invitation or submission of any inquiries, proposals
or offers or any other efforts or attempts that constitute, or may reasonably be
expected to lead, to any CRA Acquisition Proposal (as hereinafter defined) from
any person or engage in any discussions or negotiations with respect thereto or
otherwise
 
                                       45
<PAGE>
cooperate with or assist or participate in, or facilitate, any such proposal;
provided, however, that, notwithstanding any other provision of the
Reorganization Agreement, (i) the CRA Board may take and disclose to the
stockholders of CRA a position contemplated by Rule 14e-2(a) promulgated under
the Exchange Act and (ii) following receipt from a third party, without any
solicitation, initiation or encouragement, directly or indirectly, by CRA or any
CRA representative, of a bona fide CRA Acquisition Proposal, (x) CRA may engage
in discussions or negotiations with such third party and may furnish such third
party information concerning it and its business, properties and assets if such
third party executes a confidentiality agreement in reasonably customary form
and (y) the CRA Board may withdraw, modify or not make its recommendation to
adopt and approve the CRA Proposal or terminate the Reorganization Agreement, in
each case referred to in the foregoing clauses (i) and (ii), only to the extent
that the CRA Board shall conclude in good faith based on the advice of CRA's
outside counsel that such action is necessary in order for the CRA Board to act
in a manner that is consistent with its fiduciary obligations under applicable
law. As used in the Reorganization Agreement, "CRA Acquisition Proposal" means
any proposal or offer made by a person or group of persons other than a proposal
or offer by OccuSystems or any of its affiliates (which person or group has, in
the good faith determination of the CRA Board, the financial ability to
consummate such proposal or offer), for, or that could be reasonably expected to
lead to, a tender or exchange offer, a merger, consolidation or other business
combination involving such person or group and CRA or any CRA Significant
Subsidiaries (as defined in the Reorganization Agreement) or any proposal from
any such person or group to acquire in any manner a substantial equity interest
in, or any substantial portion of the assets of, CRA or any CRA Significant
Subsidiaries.
 
    OCCUSYSTEMS ALTERNATIVE PROPOSALS.  Pursuant to the Reorganization
Agreement, OccuSystems has agreed that it will not, and will not authorize or
(to the extent within its control) permit any of its officers, directors,
employees, agents, affiliates and other representatives or those of any of its
subsidiaries to, directly or indirectly, solicit or encourage (including by way
of providing information) any prospective acquiror or the invitation or
submission of any inquiries, proposals or offers or any other efforts or
attempts that constitute, or may reasonably be expected to lead, to any
OccuSystems Acquisition Proposal (as hereinafter defined) from any person or
engage in any discussions or negotiations with respect thereto or otherwise
cooperate with or assist or participate in, or facilitate, any such proposal;
provided, however, that, notwithstanding any other provision of the
Reorganization Agreement, (i) the OccuSystems Board may take and disclose to the
stockholders of OccuSystems a position contemplated by Rule 14e-2(a) promulgated
under the Exchange Act and (ii) following receipt from a third party, without
any solicitation, initiation or encouragement, directly or indirectly, by
OccuSystems or any OccuSystems representative, of a bona fide OccuSystems
Acquisition Proposal, (x) OccuSystems may engage in discussions or negotiations
with such third party and may furnish such third party information concerning it
and its business, properties and assets if such third party executes a
confidentiality agreement in reasonably customary form and (y) the OccuSystems
Board may withdraw, modify or not make its recommendation to adopt and approve
the OccuSystems Proposal or terminate the Reorganization Agreement, but in each
case referred to in the foregoing clauses (i) and (ii), only to the extent that
the OccuSystems Board shall conclude in good faith based on the advice of
OccuSystems' outside counsel that such action is necessary in order for the
OccuSystems Board to act in a manner that is consistent with its fiduciary
obligations under applicable law. As used in the Reorganization Agreement,
"OccuSystems Acquisition Proposal" means any proposal or offer made by a person
or group of persons other than a proposal or offer by CRA or any of its
affiliates (which person or group has, in the good faith determination of the
OccuSystems Board, the financial ability to consummate such proposal or offer),
for, or that could be reasonably expected to lead to, a tender or exchange
offer, a merger, consolidation or other business combination involving such
person or group and OccuSystems or any OccuSystems Significant Subsidiaries (as
defined in the Reorganization Agreement) or any proposal from any such person or
group to acquire in any manner a substantial equity interest in, or any
substantial portion of the assets of, OccuSystems or any OccuSystems Significant
Subsidiaries.
 
                                       46
<PAGE>
    EMPLOYEE BENEFITS.  Concentra has agreed in the Reorganization Agreement
that it will cause to be in effect immediately following the Effective Time
employee benefit plans for the benefit of CRA's and OccuSystems' employees that
are reasonably comparable in the aggregate to the employee benefit plans for
such employees that were in effect immediately prior to the Effective Time.
 
    MEETINGS OF STOCKHOLDERS.  Pursuant to the Reorganization Agreement, both
OccuSystems and CRA have agreed to take all necessary action, in accordance with
applicable law and their respective charters and bylaws, to promptly convene the
Special Meetings. OccuSystems and CRA have also agreed, subject to the exercise
of the fiduciary duties of their respective Boards of Directors, to recommend
such approval and to take all lawful action to solicit such approvals.
 
    INDEMNIFICATION AND INSURANCE.  The Reorganization Agreement provides that,
from and after the Effective Time, Concentra will indemnify, defend and hold
harmless to the fullest extent that OccuSystems or CRA would have been permitted
under applicable law, each person who was, as of the date of the Reorganization
Agreement, or has been at any time prior to the date of the Reorganization
Agreement, an officer or director of OccuSystems or CRA (individually an
"Indemnified Party" and collectively the "Indemnified Parties"), against all
losses, claims, damages, liabilities, costs or expenses (including attorneys'
fees), judgments, fines, penalties and amounts paid in settlement in connection
with any claims, suits, actions, proceedings or investigations arising out of or
pertaining to acts or omissions, or alleged acts or omissions, made by them in
their capacities as officers and directors. The Reorganization Agreements also
provides that Concentra will maintain, and cause CRA to keep in effect,
provisions of their charter and bylaws providing for exculpation of director and
officer liability and indemnification of the Indemnified Parties to the fullest
extent permitted under applicable law. The Reorganization Agreement also
provides that, for a period of six years after the Effective Time, directors'
and officers' liability insurance will be maintained covering the Indemnified
Parties who are currently covered, in their capacities as directors and
officers, by OccuSystems' and CRA's existing directors' and officers' liability
insurance policies on terms no less advantageous to the Indemnified Parties than
such existing insurance to the extent such coverage can be maintained or
procured by the payment of an annual premium not exceeding one and one-half
times the current annual premium paid by OccuSystems for its existing coverage
(which current annual premium is approximately $110,000).
 
    OTHER ACTIONS.  Pursuant to the Reorganization Agreement, both CRA and
OccuSystems have agreed to use their reasonable efforts to take, or cause to be
taken, all other action and to do, or cause to be done, all other things
necessary, proper or appropriate to consummate the transactions contemplated by
the Reorganization Agreement.
 
    CERTAIN OTHER COVENANTS.  Both OccuSystems and CRA have also agreed (i) to
promptly make their respective filings, and any other submissions, under the HSR
Act and obtain all other consents, approvals or permits from the necessary
Federal and state governments and regulatory agencies prior to the Effective
Time, (ii) to allow all designated officers, attorneys, accountants and
representatives of the other reasonable access to the offices, records and files
and to instruct their respective employees, counsel and financial advisors to
cooperate with each other's investigation, (iii) to consult with each other
prior to issuing any press release or public statement, (iv) to cooperate in the
filing of the Registration Statement and obtaining all necessary state
securities laws permits or approvals, (v) to cause Concentra to submit an
application to the Nasdaq National Market covering the Concentra Common Stock to
be issued in the Mergers and to use reasonable efforts to obtain the approval of
such application prior to the Effective Time, (vi) to use all reasonable efforts
to deliver or cause to be delivered to Concentra an affiliate letter, in the
form attached to the Reorganization Agreement, from each of the OccuSystems
Affiliates and the CRA Affiliates prior to the Closing Date, (vii) to pay all
costs and expenses incurred by it except (a) HSR filing fees, (b) Registration
Statement filing fees, (c) expenses of Concentra, and (d) costs of printing and
mailing this Joint Proxy Statement/Prospectus, which shall be shared equally by
OccuSystems and CRA, (ix) to take such actions as are necessary to minimize or
eliminate the effects of any antitakeover statute or
 
                                       47
<PAGE>
regulation, (x) to cause Concentra and CRA Merger Sub to perform their
obligations under the Reorganization Agreement and not to perform any other
function, and (xi) to cooperate in the filing of all returns, questionnaires,
applications or other documents relating to any taxes or fees that become
payable in connection with the Mergers.
 
CONDITIONS TO THE MERGERS
 
    The obligations of OccuSystems and CRA to consummate the Mergers are
conditioned on the fulfillment of the following conditions: (i) approval, in the
manner required by law or the applicable requirements of the Nasdaq National
Market, by the stockholders of OccuSystems and CRA, of the OccuSystems Proposal
and the CRA Proposal, respectively; (ii) expiration or termination of the
applicable waiting period under the HSR Act; (iii) neither CRA nor OccuSystems
shall be subject to any order or injunction of a court of competent jurisdiction
which prohibits the consummation of the transactions contemplated by the
Reorganization Agreement; (iv) the effectiveness of the Registration Statement
and the absence of any stop order suspending the effectiveness thereof and no
proceeding for that purpose having been initiated by the Commission; (v) the
receipt of all consents, authorizations, orders and approvals of (or filings or
registrations with) any governmental commission, board or other regulatory body
required in connection with the execution, delivery and performance of the
Reorganization Agreement (except for those documents required to be filed after
the Effective Time and except where the failure to obtain such approval or order
would not have a material adverse effect on Concentra); and (vi) the approval
for quotation of the Concentra Common Stock on the Nasdaq National Market,
subject only to official notice of issuance.
 
    The obligation of OccuSystems to consummate the Mergers is conditioned on
the fulfillment of the following additional conditions: (i) the performance by
CRA, in all material respects, of its obligations required to be performed on or
prior to the Closing Date and contained in the Reorganization Agreement, and the
representations and warranties made by CRA in the Reorganization Agreement being
true and correct as of the Closing Date; (ii) the receipt by OccuSystems of an
opinion from tax counsel stating that the OccuSystems Merger will be treated as
a reorganization described in Section 368(a) of the Code; (iii) no material
adverse change in the business, financial condition or operations of CRA shall
have occurred; (iv) holders of not more than five percent of the outstanding
shares of CRA Common Stock have perfected appraisal rights; (v) receipt of an
opinion from OccuSystems' independent auditors that the Mergers would be
properly accounted for as a pooling-of-interests; and (vi) DLJ's fairness
opinion shall have been reissued at the time of mailing this Joint Proxy
Statement/Prospectus and shall not have been withdrawn or materially modified by
DLJ in a manner adverse to OccuSystems stockholders.
 
    The obligation of CRA to consummate the Mergers is conditioned on the
fulfillment of the following additional conditions, (i) the performance by
OccuSystems, in all material respects, of its obligations required to be
performed on or prior to the Closing Date and contained in the Reorganization
Agreement and the representations and warranties made by OccuSystems in the
Reorganization Agreement being true and correct in all material respects as of
the Closing Date, (ii) the receipt by CRA of a satisfactory opinion of its
special counsel that the CRA Merger will be treated as a reorganization within
the meaning of Section 368(a) of the Code and/or the transfer of property
governed by Section 351 of the Code, (iii) the receipt by OccuSystems and
Concentra of the tax opinion described in the preceding paragraph, (iv) no
material adverse change in the business, financial condition or operations of
OccuSystems shall have occurred, (v) receipt of an opinion dated as of the
Closing Date from CRA's auditors that the Mergers would be properly accounted
for as a pooling of interest, and (vi) Alex. Brown's fairness opinion shall not
have been withdrawn or materially modified by Alex. Brown in a manner adverse to
CRA's stockholders.
 
TERMINATION OF THE REORGANIZATION AGREEMENT
 
    The Reorganization Agreement is subject to termination by the mutual consent
of OccuSystems and CRA. The Reorganization Agreement may also be terminated by
either party if (i) the Mergers are not
 
                                       48
<PAGE>
consummated on or before October 31, 1997, (ii) either CRA's or OccuSystems'
stockholders fail to approve the CRA Proposal or the OccuSystems Proposal,
respectively, or (iii) a United States Federal court or Federal governmental,
regulatory or administrative agency, or a state court of competent jurisdiction
or state governmental, regulatory or administrative agency or commission, issues
an order, decree or ruling permanently restraining, enjoining or otherwise
prohibiting the consummation of the Mergers, and such order, decree or ruling
has become final and non-appealable, provided that the party seeking to
terminate the Reorganization Agreement shall have used all reasonable efforts to
remove such injunction, order or decree.
 
    The Reorganization Agreement may be terminated by the OccuSystems Board at
any time prior to the Effective Time if (i) in the good faith judgment of the
OccuSystems Board, as advised by outside counsel, its fiduciary duties to its
stockholders requires such termination by reason of an OccuSystems Alternative
Proposal being made, (ii) there has been a breach by CRA of any representation
or warranty in the Reorganization Agreement, subject to certain materiality
exceptions, (iii) there has been a material breach of any of the covenants or
agreements in the Reorganization Agreement on the part of CRA which is not
curable or not cured within 30 days after written notice of the breach by
OccuSystems or (iv) the CRA Board shall have withdrawn or modified, in a manner
materially adverse to OccuSystems, its approval or recommendation of the CRA
Proposal.
 
    The Reorganization Agreement may be terminated by the CRA Board at any time
prior to the Effective Time if (i) in the good faith judgment of the CRA Board,
as advised by outside counsel, its fiduciary duties to its stockholders requires
such termination by reason of a CRA Alternative Proposal being made, (ii) there
has been a breach by OccuSystems of any representation or warranty in the
Reorganization Agreement, subject to certain materiality exceptions, (iii) there
has been a material breach of any of the covenants or agreements in the
Reorganization Agreement on the part of OccuSystems which is not curable or not
cured within 30 days after written notice of the breach by CRA or (iv) the
OccuSystems Board shall have withdrawn or modified, in a manner materially
adverse to CRA, its approval or recommendation of the OccuSystems Proposal.
 
TERMINATION FEES
 
    If a CRA Alternative Proposal is made and thereafter the Reorganization
Agreement is terminated (i) by action of the CRA Board in the exercise of its
fiduciary duties by reason of such CRA Alternative Proposal or (ii) by action of
OccuSystems if the CRA Board has withdrawn or modified, in a manner materially
adverse to OccuSystems, its approval or recommendation of the CRA Proposal, then
CRA must pay OccuSystems a termination fee of $10 million. If an OccuSystems
Alternative Proposal is made and thereafter the Reorganization Agreement is
terminated (i) by action of the OccuSystems Board in the exercise of its
fiduciary duties by reason of such OccuSystems Alternative Proposal or (ii) by
action of the CRA Board if the OccuSystems Board has withdrawn or modified in a
manner materially adverse to CRA its approval or recommendation of the
OccuSystems Proposal, then OccuSystems must pay CRA a termination fee of $10
million.
 
                          THE STOCK OPTION AGREEMENTS
 
    The following is a brief summary of the terms of the Stock Option
Agreements, copies of which are attached hereto as Appendices B and C and which
are incorporated herein by reference. Such summary is qualified in its entirety
by reference to the Stock Option Agreements.
 
GENERAL
 
    Pursuant to mutual Stock Option Agreements, CRA has granted to OccuSystems
the OccuSystems Option, and OccuSystems has granted to CRA the CRA Option. As
holders of such Options (the "Option Holders"), OccuSystems and CRA have the
right under certain circumstances to purchase, respectively, up
 
                                       49
<PAGE>
to (i) with respect to the CRA Option, ten percent of the outstanding shares of
OccuSystems Common Stock as of March 31, 1997, and (ii) with respect to the
OccuSystems Option, ten percent of the outstanding shares of CRA Common Stock as
of March 31, 1997 (shares purchasable pursuant to the CRA Option and the
OccuSystems Option are collectively referred to as the "Option Shares") at a
price of $37.875 per share for CRA Common Stock and at a price of $21.21 per
share for OccuSystems Common Stock. The exercise price is payable in cash. The
Stock Option Agreements could have the effect of making an acquisition of either
CRA or OccuSystems by a third party more costly because of the need to acquire
in any such transaction the shares of common stock of the Issuer issued under
the Stock Option Agreements. In addition, the exercise of either of the Options
may render more difficult or impossible the consummation by a third party of an
acquisition of the Issuer of such exercised Option under the
pooling-of-interests method of accounting.
 
    An Option may be exercised by the Option Holder, in whole or in part, at any
time or from time to time after the Reorganization Agreement is terminated under
circumstances that entitle such Option Holder to termination fees as described
in "THE REORGANIZATION AGREEMENT--Termination Fees" (a "Trigger Event"). The
Options will terminate upon the earlier of (i) the Effective Time, (ii) the
termination of the Reorganization Agreement pursuant to its terms (other than a
termination which is also a Trigger Event), or (iii) the 180th day following a
Trigger Event (or if, at the expiration of such period the Option cannot be
exercised by reason of any applicable judgment, decree, order, law or
regulation, ten business days after such impediment to exercise shall have been
removed or shall have become final and not subject to appeal, but in no event
under this clause (iii) later than the 548th day following such Triggering
Event).
 
    Notwithstanding the foregoing, no Option may be exercised if the Option
Holder is in material breach of any of its representations, warranties,
covenants or agreements contained in the applicable Stock Option Agreement or in
the Reorganization Agreement. In addition, the Total Profit of the Option Holder
resulting from the payment of a termination fee under the Reorganization
Agreement and the exercise of rights under its Stock Option Agreement may not
exceed $15 million. See "-- Limitation on Total Profit."
 
CERTAIN REPURCHASES
 
    Under the terms of the Stock Option Agreements, at any time during which the
Option is exercisable (the "Repurchase Period"), the Option Holder has the right
to require the Issuer to repurchase from the Option Holder all or any portion of
the Option or the Option Shares purchased pursuant to the exercise of the
Option. The amount that the Issuer must pay to the Option Holder to repurchase
the Option is the difference between the Market Price (as defined below) for
shares of Issuer common stock as of the date the Option Holder gives notice of
its intent to exercise its repurchase rights (the "Notice Date") and the
exercise price for the Option, multiplied by the number of Option Shares, but
only if the Market Price is greater than such exercise price. The amount that
the Issuer must pay to the Option Holder to repurchase the Option Shares is the
exercise price paid by the Option Holder for the Option Shares plus the
difference between the Market Price and the exercise price paid by the Option
Holder for the Option Shares, but only if the Market Price is greater than such
exercise price, multiplied by the number of Option Shares. The Stock Option
Agreements define "Market Price" as the average of the closing sale prices of
shares of Issuer common stock on the Nasdaq National Market for the ten trading
days immediately preceding the Notice Date.
 
VOTING
 
    Under the terms of the Stock Option Agreements, each party has agreed to
vote, prior to the Expiration Date (as defined below under "-- Standstill
Provisions"), any shares of the capital stock of the other party acquired
pursuant to the Stock Option Agreements or otherwise beneficially owned by such
party on each matter submitted to a vote of stockholders of such other party for
and against such matter in
 
                                       50
<PAGE>
the same proportion as the vote of all other stockholders of such other party
are voted for and against such matter.
 
LIMITATION ON TOTAL PROFIT
 
    Each Stock Option Agreement limits an Option Holder's Total Profit to $15
million. As used in the Stock Option Agreements, "Total Profit" means the
aggregate amount (before taxes) of the following: (i) the termination fee
received by the Option Holder under the Reorganization Agreement; (ii) the
amount received by the Option Holder pursuant to a repurchase of the Option
Holder's Option or the Issuer's shares less the purchase price for such shares;
and (iii) the net cash amount received by the Option Holder from the sale of any
shares acquired pursuant to the Stock Option Agreement less the amount paid for
such shares. In addition, the Stock Option Agreement limits an Option Holder's
"Notional Total Profit" (as hereinafter defined) to $15 million. If the Notional
Total Profit exceeds $15 million, the Option Holder may, in its sole discretion,
increase the option exercise price to limit the Total Notional Profit to $15
million. For purposes of the Stock Option Agreement, "Notional Total Profit"
means the Total Profit determined as of the date of a notice to exercise an
Option assuming that the Option was exercised on such date for such number of
shares, and that such shares, together with all other shares of the Issuer that
the Option Holder had acquired pursuant to the Stock Option Agreement were sold
for cash at the closing market price as of the close of business on the
preceding trading day (less customary brokerage commission).
 
STANDSTILL PROVISIONS
 
    The Stock Option Agreements provide that, other than pursuant to the
Reorganization Agreement or the Stock Option Agreements, following the date of
the Stock Option Agreements and prior to the Expiration Date of the Stock Option
Agreements, without the prior written consent of the other party, neither party
shall, and neither party shall permit its affiliates to, directly or indirectly,
alone or in concert or conjunction with any other Person or Group (as defined
below), (i) in any manner acquire, agree to acquire or make any proposal to
acquire, any securities of, equity interest in, or any material property of,
such other party or any of its subsidiaries, (ii) except at the specific written
request of such other party, propose to enter into any business combination
involving such other party or any of its subsidiaries or to purchase a material
portion of the assets of such other party or any of its subsidiaries, (iii) make
or in any way participate in any "solicitation" of "proxies" (as such terms are
used in Regulation 14A promulgated under the Exchange Act) to vote, or seek to
advise or influence any Person with respect to the voting of any voting
securities of such other party or any its subsidiaries, (iv) form, join or in
any way participate in a Group with respect to any voting securities of such
other party or any of its subsidiaries, (v) seek to control or influence the
management, Board of Directors or policies of such other party, (vi) disclose
any intention, plan or arrangement inconsistent with the foregoing, (vii)
advise, assist or encourage any other Person in connection with the foregoing or
(viii) request such other party (or its directors, officers, employees or
agents) to amend or waive any provision of the Stock Option Agreements that
relate to the restrictions described in this paragraph or take any action that
may require such other party to make a public announcement regarding the
possibility of a business combination or merger with such party.
 
    For purposes of the foregoing, (i) the term "Person" means any corporation,
partnership, individual, trust, unincorporated association or other entity or
Group (within the meaning of Section 13(d)(3) of the Exchange Act), (ii) the
term "Expiration Date" with respect to any obligation or restriction imposed on
a party shall mean the earlier to occur (A) the first anniversary of the date of
the Stock Option Agreements and (B) such time as the other party shall have
suffered a Change of Control, and (iii) a "Change of Control" shall be deemed to
have occurred whenever (A) there shall be consummated (1) any consolidation or
merger of such party in which such party is not the continuing or surviving
corporation, or pursuant to which shares of such party's common stock would be
converted in whole or in part into cash, other securities or other property,
other than a merger of such party in which the holders of such party's common
 
                                       51
<PAGE>
stock immediately prior to the merger have substantially the same proportionate
ownership of common stock of the surviving corporation immediately after the
merger, or (2) any sale, lease, exchange or transfer (in one transaction or a
series of related transactions) of all or substantially all the assets of such
party, or (B) the stockholders of such party shall approve any plan or proposal
for the liquidation or dissolution of such party, or (C) any party, other than
such party or a subsidiary thereof or any employee benefit plan sponsored by
such party or a subsidiary thereof or a corporation owned, directly or
indirectly, by the stockholders of such party in substantially the same
proportions as their ownership of stock of such party, shall become the
beneficial owner of securities of such party representing 25% or more of the
combined voting power of then outstanding securities ordinarily (and apart from
rights accruing in special circumstances) having the right to vote in the
election of directors, as a result of a tender or exchange offer, open market
purchases, privately negotiated purchases or otherwise, or (D) at any time
during the period commencing on the date of the Stock Option Agreements and
ending on the Expiration Date, individuals who on the date of the execution of
the Stock Option Agreements constituted the Board of Directors of such party
shall cease for any reason to constitute at least a majority thereof, unless the
election or the nomination for election by such party's stockholders of each new
director during the period commencing on the date of the Stock Option Agreements
and ending on the Expiration Date was approved by a vote of at least two-thirds
of the directors then still in office who were directors at the date of the
Stock Option Agreements, or (E) any other event shall occur with respect to such
party that would be required to be reported in response to Item 6(e) (or any
successor provision) of Schedule 14A of Regulation 14A promulgated under the
Exchange Act.
 
RESTRICTIONS ON TRANSFER
 
    The Stock Option Agreements provide that, prior to the Expiration Date,
neither party may sell, assign, pledge or otherwise dispose of or transfer the
shares it acquires pursuant to the Stock Option Agreements (collectively, the
"Restricted Shares") except as specifically provided for in the Stock Option
Agreements. The Stock Option Agreements further provide that, following the
termination of the Reorganization Agreement, either party may sell any
Restricted Shares pursuant to a tender or exchange offer approved or
recommended, or otherwise determined to be fair and in the best interests of
such other party's stockholders, by a majority of the Board of Directors of such
other party. In addition to the repurchase rights described above under "Certain
Repurchases," subsequent to the termination of the Reorganization Agreement, the
parties have the right to have such shares of the other party registered under
the Securities Act for sale in a public offering.
 
                                       52
<PAGE>
                            BUSINESS OF OCCUSYSTEMS
 
    OccuSystems is the nation's largest physician practice management company
focusing on occupational healthcare. OccuSystems currently manages the practices
of 204 physicians in OccuSystems' 118 occupational healthcare centers located in
32 markets in 16 states. OccuSystems provides the management, facilities,
administrative and technical support, case management, physical therapy services
and other ancillary services necessary to establish and maintain a fully
integrated network of occupational healthcare providers. OccuSystems believes
that this network of physicians and facilities combined with OccuSystems'
management expertise and cost containment programs provide significant
advantages to patients, employers, physicians and payors in reducing the overall
costs associated with occupational healthcare. Since December 1, 1991,
OccuSystems has acquired the assets of 113 physician practices and developed 27
physician practices.
 
    OccuSystems believes that the decisions made by primary care physicians are
a critical determinant of the total costs (including non-medical costs) of a
workers' compensation case. Because most occupational medicine at the primary
care level is provided on a non-dedicated basis by physicians as part of their
general medical practices, OccuSystems believes that an attractive opportunity
exists in organizing primary care physicians within a national network that
exclusively provides occupational healthcare services. By so doing, OccuSystems
believes that it can substantially reduce the costs associated with occupational
healthcare while maintaining the quality of care.
 
    The occupational healthcare market is extremely fragmented. Individual
physicians, small group practices, local practice management companies and
hospital-based programs have accounted for the majority of providers of
occupational healthcare services. OccuSystems believes that, due to increasing
business and regulatory complexity, greater capital requirements and the
development of larger integrated networks such as OccuSystems, physicians are
seeking to affiliate with larger, professionally managed organizations.
 
    OccuSystems' strategy is as follows:
 
    - To continue to consolidate primary care physician practices specializing
      in occupational medicine to meet the needs of physicians seeking to
      affiliate with professionally managed organizations.
 
    - To continue to develop clusters of occupational healthcare centers in new
      and existing geographic markets, through the acquisition and development
      of physician practices and the formation of strategic joint ventures, to
      serve employers, payors and employees more effectively and to leverage
      management resources.
 
    - To develop and affiliate with vertically integrated networks of providers,
      including specialists and hospitals.
 
    - To employ its information systems and practice management expertise to
      optimize the performance of its centers and enhance its affiliated
      physicians' efficiency in practicing occupational medicine.
 
    - To implement its proprietary Active Injury/Illness Management ("AIM-SM-")
      program to manage the occupational injury and illness resolution process
      proactively from the moment of initial treatment to return to work.
 
    - To market its services on a case rate (per diagnosis) and capitated (fixed
      fee per employee per month) basis to employers, insurers and managed care
      organizations.
 
    OccuSystems' executive offices are located at 3010 LBJ Freeway, Suite 400,
Dallas, Texas 75234, and its telephone number at that address is (972) 484-2700.
 
                                       53
<PAGE>
                                BUSINESS OF CRA
 
    CRA provides field case management and specialized cost containment services
designed to reduce workers' compensation costs. CRA operates one of the largest
field case management organizations in North America, consisting of 119 field
case management offices with approximately 1,200 field case managers who provide
medical management and return to work services in 49 states, the District of
Columbia and Canada. CRA also provides a broad range of higher margin
specialized cost containment services from 78 service locations, including
utilization management, specialized PPO network management, telephonic case
management and retrospective medical bill review services, that are designed to
reduce costs associated with work-related injuries and automobile
accident-related injuries. Revenues from specialized cost containment services
comprised approximately 33.8% of revenues for 1996, up from approximately 27.1%
for 1995. CRA markets its services to workers' compensation insurers, TPAs,
self-insured employers and payors of automobile accident medical claims through
a direct sales and marketing organization consisting of over 150 dedicated
personnel. CRA currently has over 1,250 customers nationwide.
 
    CRA's objective is to expand and capitalize on its presence as a national
provider of comprehensive managed care services to workers' compensation payors
and to take advantage of developing opportunities in related industries. CRA's
strategy for achieving this objective is as follows:
 
    - To continue its primary focus on providing workers' compensation managed
      care services to workers' compensation insurers, third party
      administrators and self-insured employers.
 
    - To increase its penetration of large, national payors by leveraging its
      broad-based workers' compensation expertise and its existing experience
      with its base of national accounts.
 
    - To aggressively cross-sell its specialized cost containment services to
      its existing customer base.
 
    - To increase its marketing of early intervention services such as first
      report of injury, precertification, telephonic case management and access
      to PPO networks in order to promptly identify cases that have the
      potential to result in significant expenses and to control these expenses
      before they are incurred.
 
    - To capitalize on the recent introduction of managed care techniques to the
      automobile insurance market through the acquisition of QMC3, Inc.
      ("QMC3"), a leading provider of managed care services to this industry.
 
    - To continue to seek complementary strategic acquisitions, such as FOCUS
      HealthCare Management, Inc., QMC3 and Prompt Associates, Inc., to further
      expand its product offerings and enhance its opportunities for growth.
 
    CRA's executive offices are located at 312 Union Wharf, Boston,
Massachusetts 02109, and its telephone number at that address is (617) 367-2163.
 
                                       54
<PAGE>
                             BUSINESS OF CONCENTRA
 
GENERAL
 
    Concentra, the capital stock of which is owned equally by OccuSystems and
CRA, has not conducted any substantial business activities to date, other than
those incident to its formation, its execution of the Reorganization Agreement
and related agreements and its participation in the preparation of this Joint
Proxy Statement/Prospectus. Immediately following the consummation of the
Mergers, Concentra will become a holding company for CRA and its subsidiaries
and OccuSystems' subsidiaries. Accordingly, the business of Concentra, through
its wholly-owned subsidiary CRA and OccuSystems' and CRA's subsidiaries, will be
the businesses currently conducted by OccuSystems and CRA and their respective
subsidiaries. See "BUSINESS OF OCCUSYSTEMS" and BUSINESS OF CRA."
 
    Concentra's executive offices are located at 312 Union Wharf, Boston,
Massachusetts 02109, and its telephone number at that address is (617) 367-2163.
 
NEW CREDIT FACILITY
 
    Concurrently with the consummation of the Mergers, Concentra expects to
enter into a new credit facility to replace OccuSystems' and CRA's existing
credit facilities. The loan documents governing the new credit facility are
expected to contain customary covenants and restrictions relating to Concentra's
operations. The closing of the new credit facility, if obtained, is expected to
be conditioned upon, among other things, the consummation of the Mergers, the
satisfaction of certain financial requirements and the lenders' receipt of and
satisfaction with certain reports regarding Concentra's assets and operations.
 
                                       55
<PAGE>
          COMPARATIVE PER SHARE MARKET PRICE AND DIVIDEND INFORMATION
 
    The OccuSystems Common Stock and the CRA Common Stock are listed on the
Nasdaq National Market. The table below sets forth, for the calendar quarters
indicated, the reported high and low sales prices of OccuSystems Common Stock
and CRA Common Stock as reported on the Nasdaq National Market, in each case
based on published financial sources.
 
<TABLE>
<CAPTION>
                                                                               OCCUSYSTEMS COMMON     CRA COMMON STOCK
                                                                                     STOCK
                                                                              --------------------  --------------------
<S>                                                                           <C>        <C>        <C>        <C>
                                                                                HIGH        LOW       HIGH        LOW
                                                                              ---------  ---------  ---------  ---------
1995
  Second Quarter............................................................  $  20      $15 1/2    $  25      $16 1/2
  Third Quarter.............................................................   21 3/4     16 1/2     24 1/2       19
  Fourth Quarter............................................................   21 1/2     17 1/4     24 1/2     20 3/4
1996
  First Quarter.............................................................   25 3/4     17 3/4     36 3/4     22 1/8
  Second Quarter............................................................   40 3/4     22 1/4       47         34
  Third Quarter.............................................................   37 1/2       25       56 3/4       33
  Fourth Quarter............................................................     31       23 3/4     58 3/8     42 1/2
1997
  First Quarter.............................................................     28         22         50       37 1/2
  Second Quarter (through May 13, 1997).....................................   23 7/8     18 1/4     41 1/4     32 1/2
</TABLE>
 
    On April 21, 1997, the last full trading day prior to the public
announcement of the proposed Mergers, the closing price on the Nasdaq National
Market was $19 1/8 per share of OccuSystems Common Stock and $37 7/8 per share
of CRA Common Stock. On May 13, 1997, the most recent practicable date prior to
the filing of this Joint Proxy Statement/Prospectus, the closing price on the
Nasdaq National Market was $22 3/4 per share of OccuSystems Common Stock and
$39 5/8 per share of CRA Common Stock. Holders of OccuSystems Common Stock and
CRA Common Stock are urged to obtain current market quotations prior to making
any decision with respect to the Mergers.
 
    Neither CRA nor OccuSystems has ever paid dividends. The payment of future
dividends on Concentra Common Stock will be a business decision to be made by
the Board of Directors of Concentra from time to time based upon results of
operations and financial condition of Concentra and such other factors as the
Concentra Board of Directors considers relevant.
 
                                       56
<PAGE>
                                 CAPITALIZATION
 
    The following table sets forth the capitalization of OccuSystems and CRA as
of March 31, 1997, and the pro forma capitalization of Concentra after giving
effect to the Mergers prior to the inclusion of any deal fees and transition
costs. This table should be read in conjunction with the "Pro Forma Financial
Statements" included elsewhere in this Joint Proxy Statement/Prospectus and the
OccuSystems and CRA historical consolidated financial statements, including the
notes thereto, which are incorporated by reference in this Joint Proxy
Statement/ Prospectus.
<TABLE>
<CAPTION>
                                                                                     AS OF MARCH 31, 1997
                                                                            --------------------------------------
<S>                                                                         <C>           <C>          <C>
                                                                                   HISTORICAL
                                                                            -------------------------
 
<CAPTION>
                                                                            OCCUSYSTEMS       CRA       PRO FORMA
                                                                            ------------  -----------  -----------
                                                                                        (IN THOUSANDS)
<S>                                                                         <C>           <C>          <C>
Revolving Credit Facility.................................................   $       --    $   6,012    $   6,012
Current portion of long-term debt.........................................          860           40          900
6% Convertible Subordinated Notes due 2001................................       97,750           --       97,750
Other long-term debt......................................................          557           --          557
Stockholders' equity:
  Preferred Stock -- $.01 par value, none, 1,000,000 and 20,000,000
    authorized; none issued and outstanding...............................           --           --           --
  Common Stock -- $.01 par value; 50,000,000 and 40,000,000 100,000,000
    authorized; 21,579,898, 8,961,185 and 37,584,574 shares issued and
    outstanding, respectively.............................................          216           90          376
  Paid-in capital.........................................................      143,803       92,347      236,080
  Retained deficit........................................................       (7,900)     (11,650)     (19,550)
                                                                            ------------  -----------  -----------
    Total stockholders' equity............................................      136,119       80,787      216,906
                                                                            ------------  -----------  -----------
        Total capitalization..............................................   $  235,286    $  86,839    $ 322,125
                                                                            ------------  -----------  -----------
                                                                            ------------  -----------  -----------
</TABLE>
 
                                       57
<PAGE>
                        PRO FORMA FINANCIAL INFORMATION
 
                          CONCENTRA MANAGED CARE, INC.
            CONSOLIDATED PRO FORMA FINANCIAL STATEMENTS (UNAUDITED)
 
    The following unaudited consolidated pro forma financial statements give
effect to the Mergers using the pooling-of-interest method of accounting, after
giving effect to the pro forma adjustments described in the accompanying notes.
These unaudited pro forma combined financial statements have been prepared from,
and should be read in conjunction with, the historical financial statements and
notes thereto of CRA and OccuSystems which are incorporated by reference in this
Joint Proxy Statement/Prospectus.
 
    The unaudited Consolidated Pro Forma Balance Sheet gives effect to the
Mergers as if they had occurred on March 31, 1997, combining the consolidated
balance sheets of CRA and OccuSystems at March 31, 1997. The Consolidated Pro
Forma Statement of Operations for the three months ended March 31, 1997 and the
fiscal years ended December 31, 1996, 1995 and 1994 give effect to the Mergers
as if they had occurred on January 1, 1994, combining the results of operation
of CRA and OccuSystems for the three months ended March 31, 1997 and for each
year in the three year period ended December 31, 1996. The Consolidated Pro
Forma Statements of Operations give effect to CRA's purchases of Prompt
Associates, Inc. (acquired on October 28, 1996) and Focus HealthCare Management,
Inc. (acquired on April 2, 1996) on their respective acquisition dates and not
effective January 1, 1994. As such, the consolidated pro forma results of
operations include the results of these acquired companies only subsequent to
their acquisition dates.
 
    The unaudited Consolidated Pro Forma Financial Statements of Concentra do
not purport to present the financial position or results of operations of
Concentra had the Mergers been consummated at the dates indicated, nor are they
necessarily indicative of future operating results or financial position of the
merged companies. Certain reclassifications have been made to the unaudited
historical financial statements to conform to the presentation expected to be
used by Concentra.
 
    As a result of the Mergers, Concentra will incur certain deal fees and
transition costs, currently estimated at $15 to $20 million dollars (pre-tax),
in connection with consummating the Mergers and integrating the operations of
CRA and OccuSystems. These costs will consist principally of professional and
registration fees, systems modification costs, costs associated with the
elimination and consolidation of duplicate facilities, and employee severance
and relocation resulting from the Mergers. While the exact timing, nature and
amount of these transition costs are subject to change, Concentra anticipates
that this one time pre-tax charge will be recorded in the quarter in which the
Mergers are consummated. The unaudited Consolidated Pro Forma Financial
Statements do not reflect any of the costs described above.
 
                                       58
<PAGE>
                          CONCENTRA MANAGED CARE, INC.
 
                      CONSOLIDATED PRO FORMA BALANCE SHEET
 
                                  (UNAUDITED)
<TABLE>
<CAPTION>
                                                                                        MARCH 31, 1997
                                                                             -------------------------------------
<S>                                                                          <C>         <C>           <C>
                                                                                                        PRO FORMA
                                                                                CRA      OCCUSYSTEMS    COMBINED
                                                                             ----------  ------------  -----------
 
<CAPTION>
                                                                                        (IN THOUSANDS)
<S>                                                                          <C>         <C>           <C>
ASSETS
Current assets:
  Cash and cash equivalents................................................  $    1,692   $   21,577    $  23,269
  Short-term investments...................................................          --       31,097       31,097
  Accounts receivable, net.................................................      41,478       41,606       83,084
  Prepaid expenses and tax assets..........................................         939        6,631        7,570
                                                                             ----------  ------------  -----------
      Total current assets.................................................      44,109      100,911      145,020
Long-term investments......................................................          --        9,494        9,494
Property and equipment, net................................................       9,566       37,650       47,216
Intangible assets:
  Goodwill, net............................................................      48,376      106,537      154,913
  Assembled workforce and customer lists...................................          --        1,067        1,067
Other assets...............................................................         327        7,969        8,296
                                                                             ----------  ------------  -----------
                                                                             $  102,378   $  263,628    $ 366,006
                                                                             ----------  ------------  -----------
                                                                             ----------  ------------  -----------
LIABILITIES AND STOCKHOLDERS' EQUITY
Current liabilities:
  Revolving credit facilities..............................................  $    6,012   $       --    $   6,012
  Current portion of long-term debt........................................          40          860          900
  Accounts payable and accrued expenses....................................       7,025       12,643       19,668
  Accrued payroll and related expenses.....................................       6,280        1,363        7,643
  Accrued income taxes.....................................................       1,393           --        1,393
                                                                             ----------  ------------  -----------
      Total current liabilities............................................      20,750       14,866       35,616
Long-term debt.............................................................      98,307       98,307
Long-term deferred tax liabilities and other liabilities...................         841       14,336       15,177
Stockholders' equity.......................................................      80,787      136,119      216,906
                                                                             ----------  ------------  -----------
                                                                             $  102,378   $  263,628    $ 366,006
                                                                             ----------  ------------  -----------
                                                                             ----------  ------------  -----------
</TABLE>
 
                                       59
<PAGE>
                          CONCENTRA MANAGED CARE, INC.
                 CONSOLIDATED PRO FORMA STATEMENT OF OPERATIONS
                                  (UNAUDITED)
<TABLE>
<CAPTION>
                                                                               THREE MONTHS ENDED MARCH 31, 1997
                                                                              ------------------------------------
<S>                                                                           <C>        <C>           <C>
                                                                                                        PRO FORMA
                                                                                 CRA     OCCUSYSTEMS    COMBINED
                                                                              ---------  ------------  -----------
 
<CAPTION>
                                                                                (IN THOUSANDS, EXCEPT PER SHARE
                                                                                             DATA)
<S>                                                                           <C>        <C>           <C>
Revenues....................................................................  $  54,489   $   46,383    $ 100,872
Cost of services............................................................     44,156       35,787       79,943
                                                                              ---------  ------------  -----------
      Gross profit..........................................................     10,333       10,596       20,929
General and administrative expenses.........................................      4,251        4,086        8,337
Amortization of intangibles.................................................        415          775        1,190
                                                                              ---------  ------------  -----------
      Operating income......................................................      5,667        5,735       11,402
Interest expense, net.......................................................        140          773          913
Other expense, net..........................................................         --          327          327
                                                                              ---------  ------------  -----------
      Income before taxes...................................................      5,527        4,635       10,162
Provision for income taxes..................................................      2,432        1,622        4,054
                                                                              ---------  ------------  -----------
      Net income............................................................  $   3,095   $    3,013    $   6,108
                                                                              ---------  ------------  -----------
                                                                              ---------  ------------  -----------
Earnings per share..........................................................  $    0.34   $     0.14    $    0.16
                                                                              ---------  ------------  -----------
                                                                              ---------  ------------  -----------
Weighted average shares outstanding.........................................      9,102       22,316       38,572(1)
                                                                              ---------  ------------  -----------
                                                                              ---------  ------------  -----------
</TABLE>
<TABLE>
<CAPTION>
                                                                                 YEAR ENDED DECEMBER 31, 1996
                                                                             -------------------------------------
<S>                                                                          <C>         <C>           <C>
                                                                                                        PRO FORMA
                                                                                CRA      OCCUSYSTEMS    COMBINED
                                                                             ----------  ------------  -----------
 
<CAPTION>
                                                                             (IN THOUSANDS, EXCEPT PER SHARE DATA)
<S>                                                                          <C>         <C>           <C>
Revenues...................................................................  $  179,652   $  170,035    $ 349,687
Cost of services...........................................................     147,085      130,682      277,767
                                                                             ----------  ------------  -----------
      Gross profit.........................................................      32,567       39,353       71,920
General and administrative expenses........................................      14,439       15,867       30,306
Amortization of intangibles................................................         662        2,780        3,442
Nonrecurring charges.......................................................          --          964          964
                                                                             ----------  ------------  -----------
      Operating income.....................................................      17,466       19,742       37,208
Interest expense, net......................................................         199        1,773        1,972
Other expense, net.........................................................          --          836          836
                                                                             ----------  ------------  -----------
      Income before taxes..................................................      17,267       17,133       34,400
Provision for income taxes.................................................       7,166        6,100       13,266
                                                                             ----------  ------------  -----------
      Net income...........................................................  $   10,101   $   11,033    $  21,134
                                                                             ----------  ------------  -----------
                                                                             ----------  ------------  -----------
Earnings per share.........................................................  $     1.19   $     0.51    $    0.57
                                                                             ----------  ------------  -----------
                                                                             ----------  ------------  -----------
Weighted average shares outstanding........................................       8,475       22,029       37,165(1)
                                                                             ----------  ------------  -----------
                                                                             ----------  ------------  -----------
</TABLE>
 
- ------------------------
 
(1) The weighted average shares outstanding has been adjusted to reflect the
    issuance of shares in accordance with the exchange ratio stated in the
    Reorganization Agreement, whereby each share of CRA Common Stock will be
    exchanged for 1.786 shares of Concentra Common Stock and each share of
    OccuSystems Common Stock will be exchanged for one share of Concentra Common
    Stock.
 
                                       60
<PAGE>
                          CONCENTRA MANAGED CARE, INC.
 
                 CONSOLIDATED PRO FORMA STATEMENT OF OPERATIONS
 
                                  (UNAUDITED)
<TABLE>
<CAPTION>
                                                                                 YEAR ENDED DECEMBER 31, 1995
                                                                             -------------------------------------
<S>                                                                          <C>         <C>           <C>
                                                                                                        PRO FORMA
                                                                                CRA      OCCUSYSTEMS    COMBINED
                                                                             ----------  ------------  -----------
 
<CAPTION>
                                                                             (IN THOUSANDS, EXCEPT PER SHARE DATA)
<S>                                                                          <C>         <C>           <C>
Revenues...................................................................  $  146,055   $  136,986    $ 283,041
Cost of services...........................................................     122,615      107,284      229,899
                                                                             ----------  ------------  -----------
      Gross profit.........................................................      23,440       29,702       53,142
General and administrative expenses........................................      11,021       16,611       27,632
Amortization of intangibles................................................          --        1,871        1,871
Writedown of goodwill and other nonrecurring charges.......................          --          898          898
                                                                             ----------  ------------  -----------
      Operating income.....................................................      12,419       10,322       22,741
Interest expense, net......................................................       2,484        2,202        4,686
Other expense, net.........................................................          --          561          561
                                                                             ----------  ------------  -----------
  Income before taxes......................................................       9,935        7,559       17,494
Provision for income taxes.................................................       3,974        3,659        7,633
                                                                             ----------  ------------  -----------
      Net income(2)........................................................  $    5,961   $    3,900    $   9,861
                                                                             ----------  ------------  -----------
                                                                             ----------  ------------  -----------
Earnings per share.........................................................  $     0.91   $     0.22    $    0.33
                                                                             ----------  ------------  -----------
                                                                             ----------  ------------  -----------
Weighted average shares outstanding........................................       6,540       19,115       30,795(1)
                                                                             ----------  ------------  -----------
                                                                             ----------  ------------  -----------
</TABLE>
 
<TABLE>
<CAPTION>
                                                                                 YEAR ENDED DECEMBER 31, 1994
                                                                             -------------------------------------
<S>                                                                          <C>         <C>           <C>
                                                                                                        PRO FORMA
                                                                                CRA      OCCUSYSTEMS    COMBINED
                                                                             ----------  ------------  -----------
Revenues...................................................................  $  121,295   $   85,502    $ 206,797
Cost of services...........................................................     103,796       73,257      177,053
                                                                             ----------  ------------  -----------
      Gross profit.........................................................      17,499       12,245       29,744
General and administrative expenses........................................       8,753        9,922       18,675
Amortization of intangibles................................................          --          555          555
                                                                             ----------  ------------  -----------
      Operating income.....................................................       8,746        1,768       10,514
Interest expense, net......................................................       4,025        1,663        5,688
Other expense, net.........................................................         132           28          160
                                                                             ----------  ------------  -----------
  Income before taxes......................................................       4,589           77        4,666
Provision for income taxes.................................................       1,836        1,226        3,062
                                                                             ----------  ------------  -----------
      Net income (loss)(2)(3)..............................................  $    2,753   $   (1,149)   $   1,604
                                                                             ----------  ------------  -----------
                                                                             ----------  ------------  -----------
Earnings per share(3)......................................................  $     0.57   $    (0.08)   $    0.07
                                                                             ----------  ------------  -----------
                                                                             ----------  ------------  -----------
Weighted average shares outstanding........................................       4,815       14,333       22,933(1)
                                                                             ----------  ------------  -----------
                                                                             ----------  ------------  -----------
</TABLE>
 
- ------------------------
(1) The weighted average shares outstanding has been adjusted to reflect the
    issuance of shares in accordance with the Exchange Ratio stated in the
    Reorganization Agreement, whereby each share of CRA Common Stock will be
    exchanged for 1.786 shares of Concentra common stock and each share of
    OccuSystems Common Stock will be exchanged for one share of Concentra Common
    Stock.
 
(2) The net income amounts presented are before any extraordinary items and
    discontinued operations.
 
(3) The pro forma net income of $2,753,000 and earnings per share for 1994 have
    been computed as if CRA had been subject to federal and state income taxes
    during the entire period based upon an effective tax rate indicative of the
    statutory rate in effect during the period.
 
                                       61
<PAGE>
                       COMPARISON OF STOCKHOLDERS' RIGHTS
 
    At the Effective Time, the stockholders of OccuSystems and CRA will become
stockholders of Concentra. As stockholders of Concentra, their rights will be
governed by the DGCL and Concentra's Certificate of Incorporation (the
"Concentra Certificate") and Bylaws (the "Concentra Bylaws"). Following are
summaries of certain differences between (i) the rights of OccuSystems
stockholders and Concentra stockholders and (ii) the rights of CRA stockholders
and Concentra stockholders.
 
COMPARISON OF STOCKHOLDERS' RIGHTS WITH RESPECT TO CONCENTRA AND OCCUSYSTEMS
 
    Concentra and OccuSystems are both organized under the laws of the State of
Delaware. Any differences, therefore, in the rights of holders of OccuSystems
Common Stock and Concentra Common Stock arise solely from differences in their
respective certificates of incorporation and bylaws. The Concentra Certificate
and Concentra Bylaws are substantially similar to the OccuSystems Certificate of
Incorporation (the "OccuSystems Certificate") and the OccuSystems Bylaws,
respectively, except for certain matters as described herein.
 
    AUTHORIZED CAPITAL.  The total number of authorized shares of capital stock
of OccuSystems is 70,000,000 shares, consisting of 50,000,000 shares of
OccuSystems Common Stock, and 20,000,000 shares of preferred stock, no par value
(the "OccuSystems Preferred Stock"). The authorized capital of Concentra is set
forth under "DESCRIPTION OF CONCENTRA CAPITAL STOCK -- Authorized Capital
Stock."
 
    SPECIAL MEETING OF STOCKHOLDERS.  Special meetings of the stockholders of
OccuSystems may be called by the President, the Board of Directors or by the
stockholders if holders of not less than ten percent of all shares entitled to
vote at such meeting request such meeting in writing. The Concentra Certificate
does not permit stockholders to call a special meeting.
 
    WRITTEN CONSENT OF STOCKHOLDERS.  Any action may be taken by OccuSystems
stockholders without a meeting, without prior notice and without a vote, if the
stockholders having the number of votes that would be necessary to take such
action at a meeting at which all of the stockholders were present and voted
consent to the action in writing. The Concentra Certificate requires that any
action by stockholders be taken at an annual or special meeting and not by
written consent.
 
COMPARISON OF STOCKHOLDERS' RIGHTS WITH RESPECT TO CONCENTRA AND CRA
 
    Concentra is organized under the laws of the State of Delaware and CRA is
organized under the laws of the Commonwealth of Massachusetts. The following
discussion summarizes certain differences between the Concentra Certificate and
the Concentra Bylaws and the CRA Articles of Organization (the "CRA
Certificate") and the CRA Bylaws and between certain provisions of the DGCL and
MBCL affecting stockholders' rights.
 
    AUTHORIZED CAPITAL.  The total number of authorized shares of capital stock
of CRA is 41,000,000 shares, consisting of 40,000,000 shares of CRA Common Stock
and 1,000,000 shares of preferred stock, par value $.01 per share (the "CRA
Preferred Stock"). The authorized capital of Concentra is set forth under
"DESCRIPTION OF CONCENTRA CAPITAL STOCK -- Authorized Capital Stock."
 
    DIRECTORS.  The CRA Board is divided into three separate classes,
consisting, as nearly as possible, of equal numbers of directors. At each annual
meeting of stockholders, successors to the class of directors whose term expires
at that annual meeting shall be elected for a three-year term. The Concentra
Board will also be divided into three separate classes consisting, as near as
possible, of equal numbers of directors to serve three year terms.
 
                                       62
<PAGE>
    INDEMNIFICATION AND LIMITATION OF LIABILITY.  Delaware law generally permits
indemnification of officers, directors, employees and agents of a Delaware
corporation against expenses (including attorneys' fees) incurred in connection
with a derivative action and against expenses (including attorneys' fees),
judgments, fines and amounts paid in settlements incurred in connection with a
third party action, provided there is a determination by a majority vote of
disinterested directors, independent legal counsel or the stockholders that the
person seeking indemnification acted in good faith and in a manner reasonably
believed to be in, or not opposed to, the best interests of the corporation
(and, with respect to any third party criminal action or proceeding, had no
reasonable cause to believe this conduct was unlawful). Without court approval,
however, no indemnification may be made in respect of any derivative action in
which such person is adjudged liable to the corporation.
 
    Massachusetts law similarly permits indemnification of expenses in a
derivative or third-party action, except that no indemnification shall be
provided for any person with respect to any matter as to which he shall have
been adjudicated not to have acted in good faith in the reasonable belief that
his action was in the best interests of the corporation or, to the extent that
such matter relates to service with respect to any employee benefit plan, in the
best interests of the participants or beneficiaries of such benefit plan.
 
    Delaware law requires indemnification when the individual being indemnified
has successfully defended the action on the merits or otherwise. Massachusetts
law merely permits indemnification to the extent authorized in the corporation's
articles of organization or its by-laws or as set forth in a vote of
stockholders.
 
    Expenses incurred by an officer or director in defending an action may be
paid in advance under Delaware and Massachusetts law if such officer or director
undertakes to repay such amounts should it be determined ultimately that he is
not entitled to indemnification. Delaware law also permits the advancement of
expenses to employees and agents of the corporation without such an undertaking
to repay such amounts. In addition, both Delaware and Massachusetts law permit a
corporation to purchase indemnity insurance for the benefit of its officers,
directors, employees and agents whether or not the corporation would have the
power to indemnify against the liability covered by the policy.
 
    Both Delaware and Massachusetts corporations may include in their corporate
charters a provision eliminating or limiting the liability of a director in
certain circumstances to the corporation or its stockholders for monetary
damages for a breach of certain fiduciary duties as a director notwithstanding
any provision of law imposing such liability. Both the CRA Certificate and the
Concentra Certificate include such provisions.
 
    The indemnification and limitation of liability provisions of Massachusetts
law, and not Delaware law, will apply to actions of CRA's directors, officers,
employees and agents taken prior to the CRA Merger.
 
    INSPECTION RIGHTS.  Inspection rights under Delaware law are more extensive
than under Massachusetts law. Under Delaware law, stockholders, upon the
demonstration of a proper purpose, have the right to inspect a corporation's
stock ledger, stockholder lists and other books and records. Under Massachusetts
law, a corporation's stockholders have a right to inspect only the corporation's
charter, by-laws, records of all meetings of incorporators and stockholders and
transfer records.
 
    SPECIAL MEETINGS OF STOCKHOLDERS.  Pursuant to the CRA bylaws, a special
meeting of stockholders of CRA may be called by the holders of shares entitled
to cast not less than 40% of the votes at the meeting. The Concentra Certificate
does not permit stockholders to call a special meeting.
 
    ACTION BY CONSENT OF STOCKHOLDERS.  Under Massachusetts law, any action to
be taken by stockholders may be taken without a meeting only if all stockholders
entitled to vote on the matter consent to the action in writing, and a
corporation may not provide otherwise in its charter documents or by-laws. Under
Delaware law, unless the certificate of incorporation provides otherwise, any
action to be taken by the stockholders may be taken without a meeting, without
prior notice and without a vote, if the stockholders
 
                                       63
<PAGE>
having the number of votes that would be necessary to take such action at a
meeting at which all of the stockholders were present and voted consent to the
action in writing. The Concentra Certificate requires that any action by
stockholders be taken at an annual or special meeting of stockholders and not by
written consent.
 
    PROXIES.  Massachusetts law permits the authorization by a stockholder to
vote by proxy to be valid for no more than six months. Delaware law permits a
proxy to be valid for up to three years unless the proxy provides for a longer
period.
 
    APPROVAL OF BUSINESS COMBINATIONS AND ASSET SALES.  Generally, under
Massachusetts law, the affirmative vote of two-thirds of the shares of each
class of stock outstanding and entitled to vote or which would be adversely
affected by a merger or asset sale is necessary to approve a merger or a sale of
all or substantially all of the corporation's assets unless the articles of
organization provide for a lesser proportion of each class entitled to vote, but
not less than a majority. The CRA Certificate does not provide for such a lesser
proportion, so that the approval of any such merger or sale, including the CRA
Merger, requires a two-thirds vote of each class entitled to vote. Under
Delaware law, the affirmative vote of only a majority of the shares of stock
outstanding and entitled to vote are necessary to approve a merger or asset
sale.
 
    ANTI-TAKEOVER LEGISLATION.  Under Section 203 of the DGCL, certain "business
combinations" with "interested stockholders" of Delaware corporations are
subject to a three year moratorium unless specified conditions are met. Section
203 applies to Concentra. See "DESCRIPTION OF CONCENTRA CAPITAL STOCK -- Certain
Antitakeover Effects of Concentra Certificate, Concentra Bylaws and Delaware
Law."
 
    Massachusetts law contains an analogous anti-takeover law which is set forth
in Chapter 110F of the General Laws of Massachusetts. Chapter 110F does not
apply to the CRA Merger because the transaction has been approved by the CRA
Board. Chapter 110D of the Massachusetts General Laws is another anti-takeover
statute which applies to acquisitions of so-called "control shares." The bylaws
of CRA include a provision excluding CRA from the applicability of Chapter 110D.
Chapter 110D would apply to CRA, however, if the bylaws were amended to remove
such provision.
 
    DISSENTERS' RIGHTS.  Under Massachusetts law, dissenting stockholders who
follow prescribed statutory procedures are entitled to dissenters' rights in
connection with any merger or sale of substantially all the assets of a
corporation and in connection with certain mergers, reclassifications and other
transactions which may adversely affect the rights or preferences of
stockholders. See "THE MERGERS -- Dissenters' Rights." Delaware provides similar
rights in the case of a merger or consolidation of a corporation except that
such rights are not provided as to shares of a corporation listed on a national
securities exchange or designated as a national market system security on an
interdealer quotation systems by the NASD or held of record by more than 2,000
stockholders where such stockholders are required to accept in such a merger
only (i) shares of the surviving or resulting corporation, (ii) shares of a
corporation listed on a national securities exchange or held of record by more
than 2,000 holders, (iii) cash in lieu of fraction shares, or (iv) any
combination thereof. Delaware law does not provide dissenters' rights in
connection with sales of substantially all of the assets of a corporation,
reclassifications of stock or other amendments to the certificate of
incorporation which adversely affect a class of stock; provided, however, that a
corporation may provide in its certificate of incorporation that appraisal
rights shall be available as a result of an amendment to its certificate of
incorporation, a merger or a sale of all or substantially all of its assets. The
Concentra Certificate, however, does not provide for the appraisal rights
described in the preceding sentence.
 
    CLASSIFIED BOARD.  Massachusetts law requires, unless a corporation chooses
otherwise, and Delaware law permits, but does not require, a board of directors
to be divided into classes with each class having a term of office longer than
one year. Massachusetts law limits the term of directors on a classified board
to
 
                                       64
<PAGE>
five years. CRA has a classified board of directors with terms of three years.
See "-- Directors." Concentra will have a classified board of directors. See
"MANAGEMENT OF CONCENTRA -- Directors."
 
    REMOVAL OF DIRECTORS.  Under Delaware law, a director serving on the board
that is not classified may be removed with or without cause by the holders of a
majority of the outstanding shares entitled to vote at an election of directors.
In the case of a Delaware corporation having a classified board, stockholders
may effect such removal only for cause unless the certificate of incorporation
otherwise provides. Concentra has a classified board of directors and, as a
result, its directors may not be removed without cause. Under Massachusetts law,
any director or the entire board of directors may be removed, except as
otherwise provided in the articles of organization or by-laws, with or without
cause, by the holders of a majority of the shares entitled to vote at an
election of directors, except that directors of a class elected by a particular
class of stockholders may be removed only by the vote of holders of a majority
of the shares entitled to vote for the election of such directors. In addition,
directors of a classified board, such as CRA's, may only be removed for cause.
 
    CHANGE IN NUMBER OF DIRECTORS.  Under Massachusetts law, the number of
directors is determined in the manner provided in the corporation's by-laws. The
board of directors may be enlarged by the stockholders or, if authorized by the
by-laws, by vote of a majority of directors. CRA's by-laws fix the number of
directors at not less than three, unless there are fewer than three
stockholders, in which case there can be as few directors as stockholders. The
number of directors of CRA is determined by the stockholders.
 
    Under Delaware law, the number of directors shall be fixed by or in the
manner provided in the by-laws unless the number of directors is fixed in the
corporation's certificate of incorporation. Neither the Concentra Certificate
nor the Concentra Bylaws specify a particular number of directors.
 
    INTERESTED DIRECTOR TRANSACTIONS.  Delaware law provides that no transaction
between a corporation and a director or officer, or any entity in which any of
them have an interest, is void or voidable solely for this reason, solely
because the director or officer is present at or participates in the meeting of
the board or committee which authorizes the contract or transaction, or solely
because of his or their votes are counted for such purpose if (i) after full
disclosure the transaction is approved by the disinterested directors, which may
be less than a quorum, or the stockholders or (ii) the transaction is fair to
the corporation at the time it is approved. Massachusetts law only expressly
provides that directors who vote for and officers who knowingly participate in
loans to officers or directors are jointly and severally liable to the
corporation for any part of the loan which is not repaid, unless (i) a majority
of the directors who are not direct or indirect recipients of such loans, or
(ii) the holders of a majority of the shares entitled to vote for such
directors, have approved or ratified the loan as one which in the judgment of
such directors or stockholders, as the case may be, may reasonably be expected
to benefit the corporation.
 
    FILLING VACANCIES ON THE BOARD OF DIRECTORS,  Under Massachusetts law,
unless the articles of organization provide otherwise, any vacancy in the board
of directors, however occurring, including a vacancy resulting from enlargement
of the board and any vacancy in any other office, may be filled in the manner
prescribed in the by-laws, or, in the absence of any such provision in the
by-laws, by the directors.
 
    Under Delaware law, vacancies and newly created directorships may be filled
by a majority of directors then in office, unless otherwise provided in the
corporation's certificate of incorporation or by-laws, provided that if at the
time of filling any vacancy or newly created directorship, the directors then in
office constitute less than a majority of the entire board as constituted
immediately prior to any increase, the Delaware Court of Chancery may, upon
application of any stockholder or stockholders holding at least 10% of the total
number of shares at the time outstanding having the right to vote for such
directors, summarily order an election to be held to fill any such vacancies or
newly created directorships or to replace the directors chosen by the directors
then in office.
 
                                       65
<PAGE>
    PAYMENT OF DIVIDENDS.  There are no restrictions on authorized dividend
payments under Massachusetts law. Delaware law permits the payment of dividends
out of paid-in and earned surplus or out of net profits for the current and
preceding fiscal year.
 
                     DESCRIPTION OF CONCENTRA CAPITAL STOCK
 
    The summary of the terms of the capital stock of Concentra set forth below
does not purport to be complete and is subject to and qualified in its entirety
by reference to the Concentra Certificate and the Concentra Bylaws.
 
AUTHORIZED CAPITAL STOCK
 
    Under the Concentra Certificate, the total number of shares of all classes
of capital stock that Concentra has authority to issue is 120,000,000 shares, of
which 100,000,000 are shares of Concentra Common Stock, par value $.01 per
share, and 20,000,000 are shares of Concentra Preferred Stock, par value $.01
per share ("Concentra Preferred Stock").
 
    The additional shares of authorized capital stock available for issuance by
Concentra might be issued at such times and under such circumstances as to have
a dilutive effect on earnings per share and on the equity ownership of the
holders of Concentra Common Stock. The ability of the Concentra Board of
Directors to issue additional shares of capital stock could enhance the
Concentra Board of Directors' ability to negotiate on behalf of the stockholders
in a takeover situation and also could be used by the Concentra Board of
Directors to make a change in control more difficult, thereby denying
stockholders the potential to sell their shares at a premium and entrenching
current management.
 
COMMON STOCK
 
    Holders of Concentra Common Stock will be entitled to one vote per share on
all matters voted on generally by the stockholders, including the election of
directors, and, except as otherwise required by law or except as provided with
respect to any series of Concentra Preferred Stock, the holders of such shares
will possess all voting power. The Concentra Certificate does not provide for
cumulative voting for the election of directors. Thus, under the DGCL, the
holders of more than one-half of the outstanding shares of Concentra Common
Stock generally will be able to elect all the directors of Concentra then
standing for election and holders of the remaining shares will not be able to
elect any director.
 
    Subject to any preferential rights of any series of Concentra Preferred
Stock, holders of shares of Concentra Common Stock will be entitled to receive
dividends on such stock out of assets legally available for distribution when,
as and if authorized and declared by the Concentra Board of Directors and to
share ratably in the assets of Concentra legally available for distribution to
its stockholders in the event of its liquidation, dissolution or winding up.
 
    Holders of Concentra Common Stock will have no preferences or preemptive,
conversion or exchange rights.
 
PREFERRED STOCK
 
    The Concentra Board of Directors is authorized to issue shares of Concentra
Preferred Stock, in one or more series, and to fix for each such series the
number of shares thereof and voting powers and such preferences and relative,
participating, optional or other special rights and such qualifications,
limitations or restrictions as are permitted by the DGCL. The Concentra Board of
Directors could authorize the issuance of shares of Concentra Preferred Stock
with terms and conditions that could discourage a takeover or other transaction
that holders of some or a majority of shares of Concentra Common Stock might
believe to be in their best interests or in which such holders might receive a
premium for their shares of stock over the then market price of such shares. As
of the date hereof, no shares of Concentra Preferred
 
                                       66
<PAGE>
Stock are outstanding and the Concentra Board of Directors has no present
intention to issue any shares of Concentra Preferred Stock after the Effective
Time.
 
STOCKHOLDER RIGHTS PLAN
 
    Concentra anticipates that, immediately upon completion of the Mergers, the
Board of Directors of Concentra will declare, pursuant to a rights agreement
(the "Rights Agreement"), a dividend distribution of one common share purchase
right ("Right") for each outstanding share of Concentra Common Stock. Each Right
will entitle the registered holder to purchase from Concentra one one-thousandth
of a share of Series B Junior Participating Preferred Stock, par value $.01 per
share (the "Junior Preferred Shares"), of Concentra at a price per share to be
determined by the Board of Directors of Concentra with the advice of investment
bankers about the long-term prospects for Concentra's value (the "Purchase
Price"), subject to adjustment. Each one-thousandth of a Junior Preferred Share
will be economically equivalent to one share of Concentra Common Stock. The
Purchase Price is expected to be significantly higher than the trading price of
the Concentra Common Stock. Therefore, the dividend will have no initial value
and no impact on the financial statements of Concentra. The following summary of
the Rights does not purport to be complete and is qualified in its entirety by
reference to the Rights Agreement, which is an exhibit to the Registration
Statement.
 
    Initially, the Rights will be attached to all certificates representing
shares of Concentra Common Stock then outstanding, and no separate certificates
representing the Rights will be distributed. Subject to extension by a majority
of the Continuing Directors (as defined in the Rights Agreement) acting on
behalf of Concentra, the Rights will separate from the Concentra Common Stock
upon the Distribution Date, which is defined as the earlier of (a) ten days
following a public announcement that a person or group of affiliated or
associated persons has acquired, or obtained the right to acquire, beneficial
ownership of 15% or more of the outstanding shares of Concentra Common Stock or
that a majority of the Continuing Directors has identified a person or group of
affiliated or associated persons as holding a substantial interest in Concentra
(which interest must be 10% or more of the outstanding shares of Common Stock)
with an intent that is adverse to Concentra (any of the foregoing persons being
an "Acquiring Person"), or (b) ten business days following the commencement of a
tender offer or exchange offer that would result in a person or group
beneficially owning 15% or more of such outstanding shares of Concentra Common
Stock. Until the Distribution Date, (i) the Rights will be evidenced by the
Concentra Common Stock certificates and will be transferred with and only with
the Concentra Common Stock certificates, (ii) all certificates representing
shares of Concentra Common Stock will contain a notation incorporating the
Rights Agreement by reference and (iii) the surrender for transfer of any
certificate for Concentra Common Stock outstanding will also constitute the
transfer of the Rights associated with the Concentra Common Stock represented by
that certificate. As soon as practicable after the Distribution Date, separate
certificates evidencing the Rights will be mailed to holders of record of the
Concentra Common Stock.
 
    The Rights are not exercisable until the Distribution Date and will expire
ten years after consummation of the Mergers, unless earlier redeemed by
Concentra.
 
    In the event that, at any time following the Distribution Date, (a)
Concentra is the surviving corporation in a merger or combination with an
Acquiring Person and the shares of Concentra Common Stock shall remain
outstanding and not be changed or exchanged, (b) a person becomes the beneficial
owner of 15% or more of the then outstanding shares of Concentra Common Stock,
(c) an Acquiring Person engages in one or more "self-dealing" transactions as
set forth in the Rights Agreement or (d) a person is determined to hold a
substantial interest in Concentra (which interest must be 10% or more of the
outstanding shares of Concentra Common Stock) with an intent that is adverse to
Concentra, each holder of a Right will thereafter have the right to receive,
upon exercise, Junior Preferred Shares (or, in certain circumstances, Concentra
Common Stock, cash, property or other securities of Concentra) having a value
equal to two times the exercise price of the Right. For example, at an exercise
price of $100.00 per Right, each Right not owned by an Acquiring Person
following an event described above would entitle its
 
                                       67
<PAGE>
holder to purchase from Concentra $200.00 worth of Junior Preferred Shares (or
in certain circumstances, Concentra Common Stock, cash, property or other
securities of Concentra) for $100.00. Assuming that the Concentra Common Stock
had a current market price per share of $20.00 at that time, the holder of each
valid Right would be entitled to purchase ten one-thousandths of Junior
Preferred Shares for $100.00. Notwithstanding the foregoing, following the
occurrence of any of the events set forth in this paragraph, all Rights that
are, or (under certain circumstances specified in the Rights Agreement) were,
beneficially owned by an Acquiring Person will be null and void. However, Rights
are not exercisable following the occurrence of any of the events set forth
above until such time as the Rights are no longer redeemable by Concentra as set
forth below.
 
    In the event that, at any time following the date that a person has become
an Acquiring Person (the "Shares Acquisition Date"), (a) Concentra is acquired
in a merger or other combination transaction in which Concentra is not the
surviving entity, (b) Concentra consolidates with or merges with or into any
other person pursuant to which Concentra is the surviving entity but all or a
part of the shares of Concentra Common Stock are changed into or exchanged for
stock of another person or cash or other property or (c) 50% or more of
Concentra's assets or earning power is sold or transferred, each holder of a
Right (except Rights that previously have been voided as described above) shall
thereafter have the right to receive, upon exercise, common stock or other
securities of the acquiring company having a value equal to two times the
exercise price of the Right.
 
    The Purchase Price payable and the number of Junior Preferred Shares or
other securities or property issuable upon exercise of the Rights are subject to
adjustment from time to time to prevent dilution (a) in the event of a stock
dividend on, or a subdivision, combination or reclassification of, the Concentra
Common Stock, (b) upon the grant to holders of Concentra Common Stock of certain
rights or warrants to subscribe for Concentra Common Stock or convertible
securities at less than the current per-share market price of the Concentra
Common Stock or (c) upon the distribution to holders of Concentra Common Stock
of evidences of indebtedness or assets of Concentra (excluding regular periodic
cash dividends at a rate approved by the majority of Continuing Directors of
Concentra or dividends payable in Concentra Common Stock) or of subscription
rights or warrants (other than those referred to above).
 
    With certain exceptions, no adjustment to the Purchase Price will be
required until cumulative adjustments require an adjustment of at least 1% to
the Purchase Price. Upon the exercise of a Right, Concentra will not be required
to issue fractional Junior Preferred Shares or fractional shares of Concentra
Common Stock (other than fractions in multiples of one one-thousandth of a
Junior Preferred Share) and, in lieu thereof, an adjustment in cash may be made
based on the market price of the Junior Preferred Shares or Concentra Common
Stock on the last trading date prior to the date of exercise.
 
    At any time until 15 business days following the Shares Acquisition Date,
Concentra may redeem the Rights in whole, but not in part, at a price of $.01
per Right, payable in cash. Immediately upon the action of the Concentra Board
of Directors ordering redemption of the Rights, the Rights will terminate and
the only right of the holders of Rights will be to receive the $.01 redemption
price.
 
    Until a Right is exercised, the holder thereof, as such, will have no rights
as a stockholder of Concentra, including, without limitation, the right to vote
or to receive dividends. While the distribution of the Rights will not be
taxable to stockholders or to Concentra, stockholders may, depending upon the
circumstances, recognize taxable income in the event that any of the Rights are
exercised for Concentra Common Stock (or other consideration) or for common
stock or other securities of the acquiring company as set forth above.
 
    Any of the provisions of the Rights Agreement, other than those provisions
relating to the principal economic terms of the Rights, may be amended by the
Concentra Board of Directors before the Distribution Date, and no stockholder
approval will be sought for noneconomic amendments to the Rights Agreement
except as required by law or by the rules of any national securities exchange on
which the Concentra Common Stock is then listed. After the Distribution Date,
the provisions of the Rights
 
                                       68
<PAGE>
Agreement may be amended by the Concentra Board of Directors to cure any
ambiguity, to make changes that do not adversely affect the interests of holders
of Rights (excluding the interests of any Acquiring Person) or to shorten or
lengthen any time period under the Rights Agreement; provided, however, that no
amendment to adjust the time period governing redemption may be made when the
Rights are not redeemable.
 
    The Rights have certain anti-takeover effects. The rights will cause
substantial dilution to any person or group that attempts to acquire Concentra
without conditioning the offer on the acquisition of a substantial number of
Rights. The Rights should not interfere with any merger or other business
combination approved by the Board of Directors of Concentra because the Board of
Directors may, at its option, at any time before the close of business on the
earlier of the 15th day following the Shares Acquisition Date or ten years after
the Effective Date, redeem all, but not less than all, of the then outstanding
Rights at $.01 per Right.
 
CONVERTIBLE SUBORDINATED NOTES
 
    The OccuSystems Notes were issued pursuant to an indenture (the "Indenture")
dated as of December 24, 1996, by and between OccuSystems and United States
Trust Company of New York, as trustee (the "Trustee"). The following summary of
the terms of the OccuSystems Notes and the Indenture does not purport to be
complete and is subject to, and is qualified in its entirety by, reference to
all of the provisions of the Indenture, which is filed as an exhibit to this
Registration Statement. Capitalized terms used herein without definition have
the meanings ascribed to them in the Indenture.
 
    Upon consummation of the Mergers, Concentra will assume an aggregate of
$97,750,000 of OccuSystems Notes. The OccuSystems Notes will be convertible into
3,291,243 shares of Concentra Common Stock at the initial conversion price (the
"Conversion Price") of $29.70 per share (equivalent to a conversion rate of
33.67 shares per $1,000 principal amount of Notes), subject to adjustment in
certain events. The OccuSystems Notes are currently convertible into OccuSystems
Common Stock and, subsequent to the consummation of the Mergers, will be
convertible at the option of the holders into shares of Concentra Common Stock
until the close of business on the stated maturity of the OccuSystems Notes,
unless previously redeemed or repurchased.
 
    Interest on the Notes is payable semi-annually on June 15 and December 15 of
each year, commencing on June 15, 1997. The OccuSystems Notes will be
redeemable, in whole or in part, at the option of Concentra, at any time on or
after December 15, 1999, at the redemption prices set forth in the Indenture,
plus accrued and unpaid interest and liquidated damages, if any, to the date of
redemption. Concentra will be required to offer to purchase the OccuSystems
Notes upon a Change of Control (as defined in the Indenture) at 100% of the
principal amount thereof, plus accrued and unpaid interest and liquidated
damages, if any, to the date of purchase.
 
    The OccuSystems Notes will be unsecured, general obligations of Concentra,
subordinated in right of payment to all existing and future Senior Indebtedness
(as defined in the Indenture) of Concentra. The Indenture does not contain any
financial covenants or any restrictions on the payment of dividends, the
repurchase of securities of Concentra or the incurrence of Senior Indebtedness.
 
    Consummation of the Mergers will not constitute a change in control under
the Indenture.
 
TRANSFER AGENT AND REGISTRAR
 
    The transfer agent and registrar for the Concentra Common Stock will be
                .
 
CERTAIN ANTITAKEOVER EFFECTS OF CONCENTRA CERTIFICATE, CONCENTRA BYLAWS AND
  DELAWARE LAW
 
    GENERAL.  Certain provisions of the Concentra Certificate, the Concentra
Bylaws and the DGCL may have the effect of impeding the acquisition of control
of Concentra by means of a tender offer, a proxy
 
                                       69
<PAGE>
fight, open market purchases or otherwise in a transaction not approved by the
Concentra Board of Directors.
 
    The provisions of the Concentra Certificate, the Concentra Bylaws and the
DGCL described below are designed to reduce, or have the effect of reducing, the
vulnerability of Concentra to an unsolicited proposal for the restructuring or
sale of all or substantially all of the assets of Concentra or an unsolicited
takeover attempt is unfair to Concentra stockholders. The summary of such
provisions set forth below does not purport to be complete and is subject to and
qualified in its entirety by reference to the Concentra Certificate, the
Concentra Bylaws and the DGCL.
 
    CLASSIFIED BOARD.  The Concentra Certificate provides that the Concentra
Board of Directors be divided into three classes, and, after an initial term,
each director will be elected for a three-year term. See "MANAGEMENT OF
CONCENTRA -- Directors."
 
    BUSINESS COMBINATIONS.  Section 203 of the DGCL restricts a wide range of
transactions ("business combinations") between a corporation and an interested
stockholder. An "interested stockholder" is, generally, any person who
beneficially owns, directly or indirectly, 15% or more of the corporation's
outstanding voting stock. Business combinations are broadly defined to include
(i) mergers or consolidations with, (ii) sales or other dispositions of more
than 10% of the corporation's assets to, (iii) certain transactions resulting in
the issuance or transfer of any stock of the corporation or any subsidiary to,
(iv) certain transactions which would result in increasing the proportionate
share of stock of the corporation or any subsidiary owned by, or (v) receipt of
the benefit (other than proportionately as a stockholder) of any loans, advances
or other financial benefits by, an interested stockholder. Section 203 provides
that an interested stockholder may not engage in a business combination with the
corporation for a period of three years from the time of becoming an interested
stockholder unless (i) the board of directors approved either the business
combination or the transaction which resulted in the person becoming an
interested stockholder prior to the time such person became an interested
stockholder, (ii) upon consummation of the transaction which resulted in the
person becoming an interested stockholder, that person owned at least 85% of the
corporation's voting stock (excluding shares owned by persons who are officers
and also directors and shares owned by certain employee stock plans) or (iii)
the business combination is approved by the board of directors and authorized by
the affirmative vote of at least two-thirds of the outstanding voting stock not
owned by the interested stockholder. The restrictions on business combinations
with interested stockholders contained in Section 203 do not apply to a
corporation whose certificate of incorporation contains a provision expressly
electing not to be governed by the statute. The Concentra Certificate does not
contain a provision electing to "opt-out" of Section 203.
 
    SPECIAL MEETINGS; PROHIBITION OF ACTIONS BY WRITTEN CONSENT.  Pursuant to
the DGCL, a special meeting of stockholders may be called by the board of
directors or by any other person authorized to do so in the certificate of
incorporation or the bylaws. The Concentra Certificate provides that special
meetings of stockholders may only be called by the Concentra Board of Directors,
the Chairman of the Concentra Board of Directors or the President of Concentra.
In addition, the Concentra Certificate provides that any action required or
permitted to be taken at any annual or special meeting of stockholders may be
taken only upon the vote of the stockholders at an annual or special meeting,
and may not be taken by a written consent of the stockholders.
 
                                       70
<PAGE>
                            MANAGEMENT OF CONCENTRA
 
DIRECTORS
 
    The following table sets forth information as to the persons who are
expected to serve as directors of Concentra immediately following the Effective
Time.
 
<TABLE>
<CAPTION>
NAME                                                    AGE                           POSITION
- ---------------------------------------------------  ---------  -----------------------------------------------------
<S>                                                  <C>        <C>
John K. Carlyle....................................         42  Chairman of the Board
Donald J. Larson...................................         46  Director, President and Chief Executive Officer
George H. Conrades.................................         58  Director
Robert W. O'Leary..................................         53  Director
Robert A. Ortenzio.................................         40  Director
Paul B. Queally....................................         33  Director
Mitchell T. Rabkin, M.D............................         66  Director
Lois E. Silverman..................................         56  Director
</TABLE>
 
    JOHN K. CARLYLE  has served as OccuSystems' Chairman and Chief Executive
Officer since January 1997. He joined OccuSystems in 1990 as its President and
served in that capacity until December 1996. Mr. Carlyle has served as the Chief
Executive Officer and a director of OccuSystems since 1991. From 1985 to 1990,
Mr. Carlyle served as Senior Vice President and Chief Financial Officer of
Medical Care International, Inc. ("Medical Care"), an operator of outpatient
surgical centers. Mr. Carlyle has served as a director of National Surgery
Centers, Inc., an owner and operator of free standing, multi-specialty
ambulatory surgery centers, since 1991. He also serves as a director of several
private companies. Mr. Carlyle is a certified public accountant.
 
    DONALD J. LARSON  co-founded CRA in 1978 and has served as President and
Chief Executive Officer of CRA since January 1, 1996 and as President and Chief
Operating Officer of CRA since 1988. Prior to founding CRA, Mr. Larson held the
position of New England Regional Manager at IntraCorp. Inc., a division of Cigna
Corporation.
 
    GEORGE H. CONRADES  has served as a Director of CRA since July 1994. Mr.
Conrades has been President and Chief Executive Officer of BBN Corporation, a
provider of internetworking services, products and application solutions, since
1994 and has been Chairman of the Board of BBN Corporation since November 1995.
From 1992 to 1994, Mr. Conrades was a partner in Conrades/Reilly Associates, a
business consulting company. From 1961 to 1992, Mr. Conrades held a number of
management positions with International Business Machines Corp., most recently
as Senior Vice President for Corporate Marketing and Services. Mr. Conrades is
also a director of BBN Corporation, Westinghouse Electric Corp. and Cubist
Pharmaceuticals, Inc.
 
    ROBERT W. O'LEARY  has served as a director of OccuSystems since July 1995.
Since March 1995, Mr. O'Leary has served as Chairman and Chief Executive Officer
of Premier, Inc., a voluntary healthcare alliance. From 1991 until 1995, Mr.
O'Leary served as Chairman and Chief Executive Officer of American Medical
International, Inc., a healthcare facilities management company. From 1989 to
1991, Mr. O'Leary served as President and Chief Executive Officer of Voluntary
Hospitals of America, a national hospital alliance. Previously, Mr. O'Leary
served as the Chairman of i-STAT Corporation, a medical device manufacturer.
 
    ROBERT A. ORTENZIO  has served as a director of OccuSystems since May 1992.
Mr. Ortenzio currently serves as the President of Select Medical Corporation, a
private healthcare company based in Mechanicsburg, Pennsylvania, and has served
in such capacity since August 1996. From 1986 to 1996, Mr. Ortenzio was employed
by Continental Medical Systems, Inc., a nationwide provider of rehabilitation
services, from 1986 until 1988 as its Senior Vice President, from 1988 until
June 1995 as its President and Chief Operating
 
                                       71
<PAGE>
Officer and from July 1995 to August 1996 as its President and Chief Executive
Officer. Mr. Ortenzio also served as the Executive Vice President and a director
of Horizon/CMS Healthcare Corporation from July 1995 to August 1996.
 
    PAUL B. QUEALLY  has served as a director of OccuSystems since 1993. Mr.
Queally is a general partner of Welsh, Carson, Anderson & Stowe, an investment
firm specializing in healthcare and in formation services industries. From 1993
to 1996, Mr. Queally was a general partner of The Sprout Group, a division of
Donaldson, Lufkin & Jenrette Capital Corporation, and prior thereto an associate
since 1986. Mr. Queally also serves as a director of several private companies,
including First Physician Care, a physician practice management company, and
Ortholink, Inc., an orthopedic physician practice management company.
 
    MITCHELL T. RABKIN, M.D.  has served as a Director of CRA since February
1995. From 1966 to September 1996, Dr. Rabkin served as Chief Executive Officer
of Boston's Beth Israel Hospital, where he currently holds the rank of Professor
of Medicine. Since October 1, 1996, Dr. Rabkin has been Chief Executive Officer
of CareGroup, Inc., parent corporation of Beth Israel Deaconess Medical Center.
Dr. Rabkin is a graduate of Harvard College and received his M.D. from Harvard
Medical School.
 
    LOIS E. SILVERMAN  co-founded CRA in 1978 and has served as Chairman of the
Board of CRA since March 1994 and as Chief Executive Officer of CRA from 1988 to
December 31, 1995. Prior to founding CRA, Ms. Silverman held the position of
Northeast Regional Manager at IntraCorp., a Division of Cigna Corporation. Ms.
Silverman is a director of Sun Healthcare Group, Inc., and CareGroup, Inc.,
parent corporation of Beth Israel Deaconess Medical Center, and serves as a
Trustee of Simmons College and Overseer of Tufts Medical Schools.
 
    Concentra's Certificate of Incorporation provides, among other things, for a
Board of Directors divided into three classes, designated Class I, Class II and
Class III. Directors serve for staggered terms of three years each, except that
initially the Class I directors will serve until Concentra's 1998 annual meeting
of stockholders, the Class II directors until the 1999 meeting and the Class III
directors until the 2000 meeting. The Class I directors are Messrs. Queally and
Rabkin, the Class II directors are Messrs. Ortenzio and Conrades and Ms.
Silverman, and the Class III directors are Messrs. Carlyle, O'Leary and Larson.
 
    COMPENSATION OF THE BOARD OF DIRECTORS.  Concentra anticipates paying its
non-employee directors for their services as directors an annual fee of $15,000
in restricted stock (subject to pro-rata forfeiture in the event a director
fails to attend at least 75% of board meetings in such year) and granting
options to acquire 5,000 shares of Concentra Common Stock. Each annual grant of
restricted stock and options will vest after one year. In addition, each of
Concentra's directors will receive reimbursement of all ordinary and necessary
expenses incurred in attending any meeting of the Board of Directors or any
committee of the Board of Directors.
 
    COMMITTEES OF THE BOARD OF DIRECTORS.  The Board of Directors has
established two standing committees: the Audit Committee and the Compensation
Committee. The functions of the Audit Committee will be to recommend to the
Board of Directors the appointment of independent auditors, to review the plan
and scope of any audit of Concentra's financial statements and to review
Concentra's significant accounting policies and other matters. Mr. Queally and
Ms. Silverman will serve on the Audit Committee. The functions of the
Compensation Committee will be to make recommendations to the Board of Directors
regarding the compensation of executive officers and to administer Concentra's
incentive plans. Messrs. Carlyle, Ortenzio and Conrades will serve on the
Compensation Committee. Pursuant to an agreement entered into between Ms.
Silverman and Mr. Larson, Mr. Larson has agreed to vote his shares in favor of
Ms. Silverman or her designee as a member of the Concentra Board for as long as
Ms. Silverman, her family, and trusts established by her, hold at least 519,113
shares of Concentra Common Stock.
 
                                       72
<PAGE>
OFFICERS
 
    Set forth below are the names and titles of Concentra's Chairman and
executive officers.
 
<TABLE>
<CAPTION>
            NAME AND YEAR FIRST BECAME AN
       EXECUTIVE OFFICER OF OCCUSYSTEMS OR CRA             AGE                             OFFICE
- -----------------------------------------------------      ---      -----------------------------------------------------
<S>                                                    <C>          <C>
John K. Carlyle (1990)...............................          42   Chairman of the Board
Donald J. Larson (1978)..............................          46   President and Chief Executive Officer
John A. McCarthy, Jr. (1994).........................          38   Executive Vice President of Managed Care Services
Richard A. Parr II (1996)............................          38   Executive Vice President, General Counsel and
                                                                    Secretary
Joseph F. Pesce (1994)...............................          48   Executive Vice President, Chief Financial Officer and
                                                                    Treasurer
Daniel J. Thomas (1993)..............................          38   Executive Vice President-Practice Management Services
W. Thomas Fogarty, M.D. (1985).......................          49   Senior Vice President and Chief Medical Officer
Peter R. Gates (1996)................................          45   Senior Vice President-Marketing and Sales
James M. Greenwood (1993)............................          36   Senior Vice President of Corporate Development
</TABLE>
 
    JOHN K. CARLYLE.  See "--Directors."
 
    DONALD J. LARSON.  See "--Directors."
 
    JOHN A. MCCARTHY  has served as Senior Vice President -- Cost Containment
Services and Corporate Development of CRA since August 1996. He previously
served as CRA's Vice President -- Cost Containment Services and Corporate
Development since August 1994. From June 1992 to July 1994, Mr. McCarthy was
Senior Vice President and Chief Financial Officer of MedChem Products, Inc., a
manufacturer of specialty medical products. From March 1989 to June 1992, Mr.
McCarthy was a Partner at Kaufman & Company, an investment banking firm. From
August 1987 to February 1989, Mr. McCarthy was an associate at Morgan Stanley &
Co. Incorporated, an investment banking firm.
 
    RICHARD A. PARR II  has served as OccuSystems' Executive Vice President,
General Counsel and Secretary since August 1996. Prior to joining OccuSystems,
Mr. Parr served as Vice President and Assistant General Counsel of OrNda
HealthCorp, a national hospital management company, from April 1993 through
August 1996 and as Associate General Counsel of OrNda HealthCorp from September
1991 through March 1993.
 
    JOSEPH F. PESCE  has served as Senior Vice President -- Finance and
Administration of CRA since August 1996 and as Chief Financial Officer and
Treasurer of CRA since October 1994. Mr. Pesce served as Vice President
- --Finance and Administration of CRA from October 1994 to August 1996. From
October 1981 to September 1994, Mr. Pesce held various financial positions with
Computervision Corporation and its predecessor, Prime Computer, Inc., including
Director of Corporate Planning and Analysis, Director of Leasing, Corporate
Controller, Treasurer and, most recently, Vice President -- Finance and Chief
Financial Officer. Mr. Pesce is a certified public accountant.
 
    DANIEL J. THOMAS  has served as a director of OccuSystems and its President
and Chief Operating Officer since January 1997. From April 1993 through December
1996, Mr. Thomas served as OccuSystems' Executive Vice President and Chief
Operating Officer. Prior to joining OccuSystems in 1993, Mr. Thomas served as
controller of Medical Care International, Inc. from 1987 to 1990 and as its
Senior Vice President and Divisional Director from 1990 to 1993. Mr. Thomas is a
certified public accountant.
 
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    W. THOMAS FOGARTY, M.D.  has served as OccuSystems' Senior Vice President
and Chief Medical Officer since September 1995. From 1993 to September 1995, Dr.
Fogarty served as Vice President and Medical Director of OccuSystems. From 1992
to 1993, he served as a Regional Medical Director of OccuSystems and, from 1985
until 1992, as a medical director of one of OccuSystems' centers.
 
    PETER R. GATES  has served as Senior Vice President -- Marketing and Sales
of CRA since August 1996. From May 1995 to July 1996, Mr. Gates was Vice
President of Mercer Management Consulting. From January 1990 to January 1995,
Mr. Gates was Manger of Business Development, and later General Manager, of the
x-ray business of GE Medical Systems.
 
    JAMES M. GREENWOOD  has served as OccuSystems' Chief Financial Officer since
he joined OccuSystems as a Vice President in 1993. Mr. Greenwood has served as a
Senior Vice President of OccuSystems since May 1994. From 1988 until he joined
OccuSystems in 1993, Mr. Greenwood served in numerous positions with Bank One,
Texas, N.A., and its predecessors, most recently as Senior Vice President and
Manager of Mergers and Acquisitions. Mr. Greenwood is a certified public
accountant.
 
COMPENSATION OF EXECUTIVE OFFICERS
 
    For information concerning the compensation paid to the Chief Executive
Officers and the other four most highly compensated executive officers of each
of OccuSystems and CRA for the 1996 fiscal year, see the 1996 Proxy Statement
for OccuSystems and the 1996 Proxy Statement for CRA, the relevant portions of
which are incorporated by reference into the OccuSystems Form 10-K and the CRA
Form 10-K, respectively. See "INCORPORATION OF CERTAIN DOCUMENTS BY REFERENCE."
 
    EMPLOYMENT AGREEMENTS.  Concentra has entered into employment agreements
with its Chairman and each of its executive officers. The employment agreements
provide for base salaries as follows: Mr. Carlyle, $340,000; Mr. Larson,
$350,000; Mr. McCarthy, $260,000; Mr. Parr, $230,000; Mr. Pesce, $260,000; Mr.
Thomas, $260,000; Dr. Fogarty, $240,000; Mr. Gates, $230,000; and Mr. Greenwood,
$230,000 (each being an "Officer"). Each of the employment agreements also
provide that bonuses, if any, will be paid at the discretion of Concentra's
Board of Directors and allows participation in any employee benefit plan adopted
by Concentra for its employees. The term of each of the agreements is two years.
Each of the agreements entitles each such individual to receive severance
payments if Concentra (i) terminates the employment agreement without Cause (as
defined in the employment agreement), (ii) the Officer terminates the agreement
for Good Reason (as defined in the employment agreement, which, for Mr. Carlyle,
includes ceasing to be Chairman of the Board of Concentra for any reason) or
(iii) Concentra does not renew the employment agreement other than because of
death or disability of the Officer. Such severance payments shall equal two
years' base salary for Messrs. Carlyle and Larson and one year's base salary for
each of the other executive officers. In addition, restricted stock and stock
options to purchase an aggregate of 330,000 shares granted by Occusystems to
Messrs. Carlyle, Thomas, Parr, Fogarty and Greenwood will accelerate upon
termination of such Officers by Concentra without Cause or by such Officers for
Good Reason.
 
    LIMITATIONS ON DIRECTORS' LIABILITY.  Concentra's Certificate of
Incorporation provides that no director of Concentra shall be personally liable
to Concentra or its stockholders for monetary damages for breach of fiduciary
duty as a director, except for liability (i) for any breach of the director's
duty of loyalty to Concentra or its stockholders, (ii) for acts or omissions not
in good faith or which involve intentional misconduct or a knowing violation of
law, (iii) in respect of certain unlawful dividend payments or stock redemptions
or repurchases or (iv) for any transaction from which the director derived an
improper personal benefit. The effect of these provisions is to eliminate the
rights of Concentra and its stockholders (through stockholders' derivative suits
on behalf of Concentra) to recover monetary damages against a director for
breach of fiduciary duty as a director (including breaches resulting from
grossly negligent behavior), except in the situations described above.
 
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    INDEMNIFICATION AGREEMENTS.  Concentra intends to enter into indemnification
agreements with each of its directors and officers at the Effective Time.
Pursuant to these agreements, Concentra will, to the extent permitted under
applicable law, indemnify these persons against all expenses, judgments, fines
and penalties incurred in connection with the defense or settlement of any
actions brought against them by reason of the fact that they are or were
directors or officers of Concentra or that they assumed certain responsibilities
at the direction of Concentra.
 
             DESCRIPTION OF CONCENTRA 1997 LONG-TERM INCENTIVE PLAN
 
    The description set forth below represents a summary of the principal terms
and conditions of the Concentra Managed Care, Inc. Long-Term Incentive Plan (the
"Concentra Incentive Plan") and does not purport to be complete. The description
is qualified in its entirety by reference to the Concentra Incentive Plan, a
copy of which is attached as Appendix G to this Joint Proxy
Statement/Prospectus.
 
GENERAL
 
    Concentra may grant awards with respect to shares of Concentra Common Stock
under the Concentra Incentive Plan to officers, directors, employees and certain
consultants and advisors. At the Effective Time, Concentra is expected to have
eight directors and approximately 5,500 employees. The awards under the
Concentra Incentive Plan include (i) incentive stock options qualified as such
under U.S. Federal income tax laws, (ii) stock options that do not qualify as
incentive stock options, (iii) stock appreciation rights ("SARs"), (iv)
restricted stock awards, and (v) performance units.
 
    The number of shares of Concentra Common Stock that may be subject to
outstanding awards under the Concentra Incentive Plan at any one time is equal
to ten percent of the total number of outstanding shares of Concentra Common
Stock (treating as outstanding all shares of Concentra Common Stock issuable
within 60 days upon exercise of stock options or conversion or exchange of
outstanding, publicly-traded convertible or exchangeable securities of
Concentra) minus the total number of shares of Concentra Common Stock subject to
outstanding awards under the Concentra Incentive Plan and any future stock-based
plan for employees or directors of Concentra. After the Effective Time, no
additional awards will be made under the existing CRA and OccuSystems
stock-based plans and only that number of shares of Concentra Common Stock
issuable upon exercise of awards granted under the existing CRA and OccuSystems
stock-based plans as of the Effective Time will be reserved for issuance in
respect of such plans by Concentra. At the Effective Time, the number of shares
authorized under the Concentra Incentive Plan will be approximately 4.2 million
(assuming no additional issuances of shares by OccuSystems or CRA). The number
of shares authorized under the Concentra Incentive Plan and the number of shares
subject to an award under the Concentra Incentive Plan will be adjusted for
stock splits, stock dividends, recapitalizations, mergers and other changes
affecting the capital stock of Concentra.
 
    The Board of Directors or any committee designated by it may administer the
Concentra Incentive Plan (the "Committee"). Concentra intends to have its
Compensation Committee administer the Concentra Incentive Plan. The Committee
has broad discretion to administer the Concentra Incentive Plan, interpret its
provisions, and adopt policies for implementing the Concentra Incentive Plan.
This discretion includes the ability to select the recipient of an award,
determine the type and amount of each award, establish the terms of each award,
accelerate vesting or exercisability of an award, extend the exercise period for
an award, determine whether performance conditions have been satisfied, waive
conditions and provisions of an award, permit the transfer of an award to family
trusts and other persons, and otherwise modify or amend any award under the
Concentra Incentive Plan. Nevertheless, no awards for more than 250,000 shares
or more than $1,000,000 million in cash may be granted to any one employee in a
calendar year.
 
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AWARDS
 
    The Committee determines the exercise price of each option granted under the
Concentra Incentive Plan. The exercise price for an incentive stock option must
not be less than the fair market value of the Concentra Common Stock on the date
of grant and the exercise price of non-qualified stock options must not be less
than 85% of the fair market value of the Concentra Common Stock on the date of
grant. Stock options may be exercised as the Committee determines, but not later
than ten years from the date of grant in the case of incentive stock options. At
the discretion of the Committee, holders may use shares of stock to pay the
exercise price, including shares issuable upon exercise of the option. Under the
Concentra Incentive Plan, each non-employee director who is a director of
Concentra as of both the day immediately preceding the annual meeting of
Concentra's stockholders and the day immediately following that annual meeting
shall automatically be granted a Nonstatutory Option for the purchase of
      shares of Concentra Common Stock effective on the date of the first
meeting of the Concentra Board following that annual meeting, whether or not
that director is in attendance at that Board meeting.
 
    An SAR may be awarded in connection with or separate from a stock option. An
SAR is the right to receive an amount in cash or stock equal to the excess of
the fair market value of a share of the Concentra Common Stock on the date of
exercise over the exercise price specified in the agreement governing the SAR
(for SARs not granted in connection with a stock option) or the exercise price
of the related stock option (for SARs granted in connection with a stock
option). An SAR granted in connection with a stock option will require the
holder, upon exercise, to surrender the related stock option or portion thereof
relating to the number of shares for which the SAR is exercised. The surrendered
stock option or portion will then cease to be exercisable. Such an SAR is
exercisable or transferable only to the extent that the related stock option is
exercisable or transferable. An SAR granted independently of a stock option will
be exercisable as the Committee determines. The Committee may limit the amount
payable upon exercise of any SAR. SARs may be paid in cash or stock, as the
Committee provides in the agreement governing the SAR.
 
    A restricted stock award is a grant of shares of Concentra Common Stock that
are nontransferable or subject to risk of forfeiture until specific conditions
are met. The restrictions will lapse in accordance with a schedule or other
conditions as the Committee determines. During the restriction period, the
holder of a restricted stock award may, in the Committee's discretion, have
certain rights as a stockholder, including the right to vote the stock subject
to the award or receive dividends on that stock. Restricted stock may also be
issued upon exercise or settlement of options, SARS or performance units.
 
    Performance units are performance-based awards payable in cash, stock or a
combination of both. The Committee may select any performance measure or
combination of measures as conditions for cash payments or stock issuances under
the Concentra Incentive Plan, except that performance measures for executive
officers must be objective measures chosen from among the following choices: (a)
total stockholder return (Concentra Common Stock appreciation plus dividends);
(b) net income; (c) earnings per share; (d) cash flow per share; (e) return on
equity; (f) return on assets, (g) revenues; (h) costs; (i) costs as a percentage
of revenues; (j) increase in the market price of Concentra Common Stock or other
securities; (k) the performance of Concentra in any of the items mentioned in
clause (a) through (j) in comparison to the average performance of the companies
included in the Nasdaq Health Services Stocks Index; or (1) the performance of
Concentra in any of the items mentioned in clause (a) through (j) in comparison
to the average performance of the companies used in a self-constructed peer
group established before the beginning of the performance period. The Committee
may choose different performance measures if the stockholders so approve, if tax
laws or regulations change so as not to require stockholder approval of
different measures in order to deduct the compensation related to the award for
federal income tax purposes, or if the Committee determines that it is in
Concentra's best interest to grant awards not satisfying the requirements of
Section 162(m) of the Code or any successor law.
 
                                       76
<PAGE>
OTHER PROVISIONS
 
    At the Committee's discretion and subject to conditions that the Committee
may impose, a participant's tax withholding with respect to an award may be
satisfied by the withholding of shares of Concentra Common Stock issuable
pursuant to the award or the delivery of previously owned shares of Concentra
Common Stock, in either case based on the fair market value of the shares.
 
    The Committee has discretion to determine whether an award under the
Concentra Incentive Plan will have change-of-control features. The Committee
also has discretion to vary the change of control features as its deems
appropriate. The following describes the change of control features that
Concentra generally expects may apply to additional awards, if any such feature
applies. An award agreement under the Concentra Incentive Plan may provide that,
upon a change of control of Concentra, (1) the holder of a stock option will be
granted a corresponding cash SAR, (2) all outstanding SARs and options will
become immediately and fully vested and exercisable in full, (3) the restriction
period on any restricted stock award will be accelerated and the restrictions
will expire, and (4) the target payout opportunity attainable under the
performance units will be deemed to have been fully earned for all performance
periods as of the effective date of the change in control and the holder will be
paid a pro rata portion of all associated targeted payout opportunities (based
on the number of complete and partial calendar months elapsed as of the change
of control) in cash within thirty days following the change of control or in
stock effective as of the change of control, for cash and stock-based
performance units, respectively. The award may also provide that it will remain
exercisable for its original term whether or not employment is terminated at or
following a change in control. In general, a change in control of Concentra
occurs in any of four situations: (1) a person other than Concentra or certain
affiliated companies or benefit plans becomes the beneficial owner of 20% or
more of the voting power of Concentra's outstanding voting securities (except
acquisitions from Concentra or in a transaction meeting the requirements of the
parenthetical exception in clause (3) below); (2) a majority of the Board of
Directors is not comprised of the members of the Board of Directors immediately
following the Mergers and persons whose elections as directors were approved by
those directors or their approved successors; (3) Concentra merges or
consolidates with another corporation or entity (whether Concentra or the other
entity is the survivor), or Concentra and the holders of the voting securities
of such other corporation or entity (or the stockholders of Concentra and such
other corporation or entity) participate in a securities exchange (other than a
merger, consolidation or securities exchange in which Concentra's voting
securities are converted into or continue to represent securities having the
majority of voting power in the surviving company, in which no person other than
that surviving company owns 20% or more of the outstanding shares of common
stock or voting shares of the surviving corporation, and in which at least a
majority of the board of directors of the surviving corporation were members of
the incumbent board of Concentra); or (4) Concentra liquidates or sells all or
substantially all of its assets, except sales to an entity having substantially
the same ownership as Concentra.
 
    If a restructure of Concentra occurs that does not constitute a change in
control of Concentra, the Committee may (but need not) cause Concentra to take
any one or more of the following actions: (1) accelerate in whole or in part the
time of vesting and exercisability of any outstanding stock options and stock
appreciation rights in order to permit those stock options and SARs to be
exercisable before, upon or after the completion of the restructure; (2) grant
each optionholder corresponding cash or stock SARS; (3) accelerate in whole or
in part the expiration of some or all of the restrictions on any restricted
stock award;.(4) treat the outstanding performance units as having fully or
partially met their targets and pay, in full or in part, the targeted payout;
(5) if the restructure involves a transaction in which Concentra is not the
surviving entity, cause the surviving entity to assume in whole or in part any
one or more of the outstanding awards under the Concentra Incentive Plan upon
such terms and provisions as the Committee deems desirable; or (6) redeem in
whole or in part any one or more of the outstanding awards (whether or not then
exercisable) in consideration of a cash payment, adjusted for withholding
obligations. A restructure generally is any merger of Concentra or the direct or
indirect transfer of all or substantially all of Concentra's assets (whether by
sale, merger, consolidation, liquidation, or otherwise) in one transaction or a
series of transactions.
 
                                       77
<PAGE>
    Without stockholder approval, the Concentra Board may not amend the
Concentra Incentive Plan to increase materially the aggregate number of shares
of Concentra Common Stock that may be issued under the Concentra Incentive Plan
(except for adjustments pursuant to the terms of the Concentra Incentive Plan).
Otherwise, the Board of Directors may at any time and from time to time alter,
amend, suspend or terminate the Concentra Incentive Plan in whole or in part and
in any way, subject to requirements that may exist in stock exchange rules or in
securities, tax and other laws from time to time. No award may be issued under
the Concentra Incentive Plan after the tenth anniversary of its initial
stockholder approval.
 
TAX IMPLICATIONS OF AWARDS
 
    Set forth below is a summary of the federal income tax consequences to
employees, directors and other participants in the Concentra Incentive Plan
("Concentra Employees") and Concentra as a result of the grant and exercise of
awards under the Concentra Incentive Plan. This summary is based on statutory
provisions, Treasury regulations thereunder, judicial decisions and IRS rulings
in effect on the date hereof.
 
    NONQUALIFIED STOCK OPTIONS; STOCK APPRECIATION RIGHTS; INCENTIVE STOCK
     OPTIONS.
 
    Concentra Employees will not realize taxable income upon the grant of a
non-qualified stock option ("NQSO") or a SAR. Upon the exercise of a SAR or
NQSO, the Concentra Employee will recognize ordinary compensation income
(subject to withholding by Concentra) in an amount equal to the excess of (i)
the amount of cash and the fair market value of the Concentra Common Stock
received over (ii) the exercise price (if any) paid therefor. The Concentra
Employee will generally have a tax basis in any shares of Concentra Common Stock
received pursuant to the exercise of a SAR, or pursuant to the cash exercise of
a NQSO, that equals the fair market value of such shares on the date of
exercise. Subject to the discussion under "-- Tax Code Limitations on
Deductibility," Concentra (or a subsidiary) will be entitled to a deduction for
federal income tax purposes that corresponds as to timing and amount with the
compensation income recognized by the Concentra Employee under the foregoing
rules.
 
    Concentra Employees eligible to receive an incentive stock option ("ISO")
will not have taxable income on the grant of an ISO. Upon the exercise of an
ISO, the Concentra Employee will not have taxable income, although the excess of
the fair market value of the shares of Concentra Common Stock received upon
exercise of the ISO ("ISO Stock") over the exercise price will increase the
alternative minimum taxable income of the Concentra Employee, which may cause
such Concentra Employee to incur alternative minimum tax. The payment of any
alternative minimum tax attributable to the exercise of an ISO would be allowed
as a credit against the Concentra Employee's regular tax liability in a later
year to the extent the Concentra Employee's regular tax liability is in excess
of the alternative minimum tax for that year.
 
    Upon the disposition of ISO Stock that has been held for the requisite
holding period (generally, at least two years from the date of grant and one
year from the date of exercise of the ISO), the Concentra Employee will
generally recognize capital gain (or loss) equal to the excess (or shortfall) of
the amount received in the disposition over the exercise price paid by the
Concentra Employee for the ISO Stock. However, if a Concentra Employee disposes
of ISO Stock that has not been held for the requisite holding period (a
"disqualifying disposition"), the Concentra Employee will recognize ordinary
compensation income in the year of the disqualifying disposition in an amount
equal to the amount by which the fair market value of the ISO Stock at the time
of exercise of the ISO (or, if less, the amount realized in the case of an arm's
length disqualifying disposition to an unrelated party) exceeds the exercise
price paid by the Concentra Employee for such ISO Stock. The Concentra Employee
would also recognize capital gain to the extent the amount realized in the
disqualifying disposition exceeds the fair market value of the ISO stock on the
exercise date. If the exercise price paid for the ISO Stock exceeds the amount
realized (in the case of an arm's-length disposition to an unrelated party),
such excess would ordinarily constitute a capital loss.
 
                                       78
<PAGE>
    Concentra and its subsidiaries will generally not be entitled to any federal
income tax deduction upon the grant or exercise of an ISO, unless the Concentra
Employee makes a disqualifying disposition of the ISO Stock. If a Concentra
Employee makes such a disqualifying disposition, Concentra (or a subsidiary)
will then, subject to the discussion below under "-- Tax Code Limitations on
Deductibility," be entitled to a tax deduction that corresponds as to timing and
amount with the compensation income recognized by the Concentra Employee under
the rules described in the preceding paragraph.
 
    Under current rulings, if a Concentra Employee transfers previously held
shares of Concentra Common Stock (other than ISO Stock that has not been held
for the requisite holding period) in satisfaction of part or all of the exercise
price of an NQSO or ISO, no additional gain will be recognized on the transfer
of such previously held shares in satisfaction of the NQSO or ISO exercise price
(although the Concentra Employee would still recognize ordinary compensation
income upon exercise of an NQSO in the manner described above). Moreover, that
number of shares of Concentra Common Stock received upon exercise which equals
the number of shares of previously held Concentra Common Stock surrendered
therefor in satisfaction of the NQSO or ISO exercise price will have a tax basis
that equals, and a holding period that includes, the tax basis and holding
period of the previously held shares of Concentra Common Stock surrendered in
satisfaction of the NQSO or ISO exercise price. Any additional shares of
Concentra Common Stock received upon exercise will have a tax basis that equals
the amount of cash (if any) paid by the Concentra Employee, plus the amount of
compensation income recognized by the Concentra Employee under the rules
described above. If a reload option is issued in connection with a Concentra
Employee's transfer of previously held Concentra Common Stock in full or partial
satisfaction of the exercise price of an ISO or NQSO, the tax consequences of
the reload option will be as provided above for an ISO or NQSO, depending on
whether the reload option itself is an ISO or NQSO.
 
    PERFORMANCE UNITS; RESTRICTED STOCK AWARDS.
 
    A Concentra Employee will recognize ordinary compensation income upon
receipt of cash pursuant to a performance unit or, if earlier, at the time the
cash is otherwise made available for the Concentra Employee to draw upon it. A
Concentra Employee will not have taxable income at the time of grant of a stock
award in the form of performance units denominated in Concentra Common Stock
("Stock Unit Award"), but rather, will generally recognize ordinary compensation
income at the time he receives Concentra Common Stock in satisfaction of the
Stock Unit Award in an amount equal to the fair market value of the Concentra
Common Stock received. In general, a Concentra Employee will recognize ordinary
compensation income as a result of the receipt of Concentra Common Stock
pursuant to a restricted stock award or performance unit in an amount equal to
the fair market value of the Concentra Common Stock when such stock is received;
provided, however, that if the stock is not transferable and is subject to a
substantial risk of forfeiture when received, the Concentra Employee will
recognize ordinary compensation income in an amount equal to the fair market
value of the Concentra Common Stock (a) when the Concentra Common Stock first
becomes transferable or is no longer subject to a substantial risk of forfeiture
in cases where the Concentra Employee does not make an valid election under
Section 83(b) of the Code or (b) when the Concentra Common Stock is received in
cases where the Concentra Employee makes a valid Section 83(b) election.
 
    A Concentra Employee will be subject to withholding for federal, and
generally for state and local, income taxes at the time he recognizes income
under the rules described above with respect to Concentra Common Stock or cash
received. Dividends that are received by a Concentra Employee prior to the time
that the Concentra Common Stock is taxed to the Concentra Employee under the
rules described in the preceding paragraph are taxed as additional compensation,
not as dividend income. The tax basis of a Concentra Employee in the Concentra
Common Stock received will equal the amount recognized by him as compensation
income under the rules described in the preceding paragraph, and the Concentra
Employee's holding period in those shares will commence on the date of receipt
of the shares.
 
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    Subject to the discussion immediately below, Concentra (or a subsidiary)
will be entitled to a deduction for federal income tax purposes that corresponds
as to timing and amount with the compensation income recognized by the Concentra
Employee under the foregoing rules.
 
    TAX CODE LIMITATIONS ON DEDUCTIBILITY.  In order for the amounts described
above to be deductible by Concentra (or a subsidiary), such amounts must
constitute reasonable compensation for services rendered or to be rendered and
must be ordinary and necessary business expenses. The ability of Concentra (or a
subsidiary) to obtain a deduction for future payments under the Concentra
Incentive Plan could also be limited by the golden parachute payment rules of
Section 280G of the Code, which prevent the deductibility of certain excess
parachute payments made in connection with a change in control of an employer-
corporation. Finally, the ability of Concentra (or a subsidiary) to obtain a
deduction for amounts paid under the Concentra Incentive Plan could be limited
by Section 162(m) of the Code, which limits the deductibility, for federal
income tax purposes, of compensation paid to certain executive officers of
Concentra to $1 million with respect to any such officer during any taxable year
of Concentra. However, an exception applies to this limitation in the case of
certain performance-based compensation. The Concentra Incentive Plan is intended
to satisfy the requirements for the performance-based exception. Concentra
intends to comply with the requirements of the Code with respect to awards under
the Concentra Incentive Plan so as to be eligible for the performance-based
exception, but Concentra may, in its sole discretion, determine that in one or
more cases it is in its best interests to not satisfy the requirements for the
performance-based exception.
 
    THE CRA BOARD RECOMMENDS THAT STOCKHOLDERS OF CRA VOTE IN FAVOR OF THE
APPROVAL OF THE CONCENTRA INCENTIVE PLAN.
 
    THE OCCUSYSTEMS BOARD RECOMMENDS THAT STOCKHOLDERS OF OCCUSYSTEMS VOTE IN
FAVOR OF THE APPROVAL OF THE CONCENTRA INCENTIVE PLAN.
 
           DESCRIPTION OF THE CONCENTRA EMPLOYEE STOCK PURCHASE PLAN
 
    The description set forth below represents a summary of the principal terms
and conditions of the Concentra Managed Care, Inc. Employee Stock Purchase Plan
(the "Concentra Employee Stock Purchase Plan") and does not purport to be
complete. Such description is qualified in its entirety by reference to the
Concentra Employee Stock Purchase Plan, a copy of which is attached at Appendix
H to this Joint Proxy Statement/Prospectus.
 
GENERAL
 
    A total of 500,000 shares of Concentra Common Stock are reserved for
issuance under the Concentra Employee Stock Purchase Plan. The purpose of the
Concentra Employee Stock Purchase Plan is to provide employees of Concentra who
participate in the Concentra Employee Stock Purchase Plan with an opportunity to
purchase Concentra Common Stock through payroll deductions. The Concentra
Employee Stock Purchase Plan, and the right of participants to make purchases
thereunder, is intended to qualify under the provisions of Sections 421 and 423
of the Code. See "-- Federal Income Tax Consequences" below.
 
    The Concentra Board of Directors or any committee designated by it may
administer the Concentra Employee Stock Purchase Plan (the "Committee").
Concentra intends to have its Compensation Committee administer the plan. The
Committee has broad discretion to administer the Concentra Employee Stock
Purchase Plan, interpret its provisions and adopt policies for implementing the
plan.
 
    Any persons (including officers of Concentra) who have been employed by
Concentra (or any of its parent or subsidiary corporations (within the meaning
of Sections 424(e) and (f) of the Code)) for at least five months and are
employed for at least 20 hours per week and more than five months in a calendar
year will be eligible to participate in the Concentra Employee Stock Purchase
Plan, subject to certain
 
                                       80
<PAGE>
limitations imposed by Section 423(b) of the Code. Eligible employees may become
participants in the Concentra Employee Stock Purchase Plan by delivering to
Concentra an agreement authorizing payroll deductions prior to the applicable
offering date.
 
OFFERING DATES
 
    The Concentra Employee Stock Purchase Plan will be implemented by two
six-month offerings during each calendar year. The offering periods will
commence on January 1 and July 1 of each year. The first offering period will
commence January 1, 1998.
 
PURCHASE PRICE
 
    The purchase price per share at which shares of Concentra Common Stock will
be sold under the Concentra Employee Stock Purchase Plan will be the lower of
85% of the fair market value of the Concentra Common Stock on the first day of
each six-month offering period and 85% of the fair market value of the Concentra
Common Stock on the last day of each offering period. The fair market value of
the Concentra Common Stock on a given date will be the last reported sales price
of the Concentra Common Stock on the Nasdaq National Market on such date.
 
    The purchase price of the shares of Concentra Common Stock to be purchased
under the Concentra Employee Stock Purchase Plan will be accumulated by payroll
deductions during each offering period. The deductions may not exceed 15% of a
participant's eligible compensation, which is defined in the Concentra Employee
Stock Purchase Plan to include all wages, salary, commissions and bonuses
received (including employee contributions to a 401(k) plan) during the offering
period. A participant may discontinue participation in the Concentra Employee
Stock Purchase Plan, but may not otherwise increase or decrease the rate of
payroll deductions at any time during the offering period. Payroll deductions
will commence on the first payday on or following the first day of the offering
period and continue at the same rate until terminated as provided in the
Concentra Employee Stock Purchase Plan. Such payroll deductions will be credited
to a book entry account for each participant.
 
PURCHASE OF STOCK; EXERCISE OF OPTION
 
    The maximum number of shares placed under option to a participant in an
offering period under the Concentra Employee Stock Purchase Plan will be the
lesser of 1,000 or that number determined by dividing the amount of the
participant's total payroll deductions during the offering period (and any
carryover amounts from the preceding offering period) by the purchase price per
share under the Concentra Employee Stock Purchase Plan. Unless a participant
withdraws from the Concentra Employee Stock Purchase Plan, such participant's
option for the purchase of shares will be exercised automatically at the end of
each offering period for the maximum number of whole shares at the applicable
price. As soon as practicable following the end of each offering period,
Concentra will cause a certificate to be issued in each participant's name
representing the total number of whole shares of Concentra Common Stock acquired
by the participant through the exercise of the option. Any balance remaining in
a participant's account following the exercise of the participant's option in an
offering period will be carried over to the next offering period.
 
    Notwithstanding the foregoing, no employee of Concentra will be permitted to
subscribe for shares of Concentra Common Stock under the Concentra Employee
Stock Purchase Plan if, immediately after the grant of the option, the employee
would own five percent or more of the voting power or value of all classes of
stock of Concentra or of any of its subsidiaries (including stock which may be
purchased under the Concentra Employee Stock Purchase Plan or pursuant to any
other options), nor will any employee be granted an option which would permit
the employee to buy pursuant to the Concentra Employee Stock Purchase Plan more
than $25,000 worth of stock (determined at the fair market value of the shares
at the time the option is granted) in any six month offering period.
 
                                       81
<PAGE>
OTHER PROVISIONS
 
    A participant's interest in a given offering under the Concentra Employee
Stock Purchase Plan may be terminated in whole, but not in part, by signing and
delivering to Concentra a notice of withdrawal from the Concentra Employee Stock
Purchase Plan. A participant may elect to withdraw from the Concentra Employee
Stock Purchase Plan at any time prior to 30 days before the last day of the
offering period. Upon a withdrawal, Concentra shall refund to the participant
the accumulated payroll deductions credited to the participant's account, and
the participant's payroll deductions and interest in the offering shall
terminate.
 
    In the event any change is made in Concentra's capitalization, such as a
stock split, stock dividend, exchange of shares, or merger, which results in an
increase or decrease in the number of outstanding shares of Concentra Common
Stock without receipt of consideration by Concentra, appropriate adjustments
will be made by the Committee in the shares subject to purchase under the
Concentra Employee Stock Purchase Plan and in the purchase price per share.
 
    An option granted to a participant under the Concentra Employee Stock
Purchase Plan may not be pledged, assigned or transferred for any reason and any
participant's attempt to do so may be treated by Concentra as an election to
withdraw from the Concentra Employee Stock Purchase Plan.
 
    The Concentra Board of Directors may at any time amend or terminate the
Concentra Employee Stock Purchase Plan, except that such termination shall not
affect options previously granted nor may any amendment make any change in an
option granted prior thereto which adversely affects the rights of any
participant without the written consent of such participant. In addition, no
amendment may be made to the Concentra Employee Stock Purchase Plan without
prior approval of the stockholders of Concentra if such amendment would
materially increase the benefits accruing to participants under the Concentra
Employee Stock Purchase Plan, increase the number of shares of Concentra Common
Stock that may be issued under the Concentra Employee Stock Purchase Plan,
change the class of individuals eligible for participation in the Concentra
Employee Stock Purchase Plan, extend the term of the Concentra Employee Stock
Purchase Plan, or cause options issued under the Concentra Employee Stock
Purchase Plan to fail to meet the requirements for employee stock purchase plans
as defined in Section 423 of the Code.
 
FEDERAL INCOME TAX CONSEQUENCES
 
    The Concentra Employee Stock Purchase Plan, and the right of participants to
make purchases thereunder, is intended to qualify under the provisions of
sections 421 and 423 of the Code. Under these provisions, no income will be
taxable to a participant at the time of grant of the option or purchase of the
shares. Upon disposition of the shares, the participant will generally be
subject to tax and the amount of the tax will depend upon the participant's
holding period. If the shares have been held by the participant for more than
two years after the date of the option grant, the lesser of (a) the excess of
the fair market value of the shares at the time of such disposition over the
purchase price or (b) the excess of the fair market value of the shares at the
date of the option grant over the purchase price will be treated as ordinary
income, and any further gain or loss will be treated as long-term capital gain
or loss. If the shares are disposed of before the expiration of this holding
period, the excess of the fair market value of the shares on the purchase date
over the purchase price will be treated as ordinary income, and any further gain
or loss on such disposition will be long-term or short-term capital gain or
loss, depending on the holding period. Concentra is not entitled to a deduction
for amounts taxed as ordinary income or capital gain to a participant except to
the extent of ordinary income reported by participants upon disposition of
shares within two years from the date of grant.
 
    The foregoing brief summary of the effect of federal income taxation upon
the participants and Concentra with respect to the purchase of shares under the
Concentra Employee Stock Purchase Plan does not purport to be complete, and
reference should be made to the applicable provisions of the Code. In addition,
this summary does not discuss tax consequences of a participant's death or the
provisions of the income tax laws of any municipality, state or foreign country
in which the participant may reside.
 
                                       82
<PAGE>
    THE CRA BOARD RECOMMENDS THAT THE STOCKHOLDERS OF CRA VOTE IN FAVOR OF THE
APPROVAL OF THE CONCENTRA EMPLOYEE STOCK PURCHASE PLAN.
 
    THE OCCUSYSTEMS BOARD RECOMMENDS THAT THE STOCKHOLDERS OF OCCUSYSTEMS VOTE
IN FAVOR OF THE APPROVAL OF THE CONCENTRA EMPLOYEE STOCK PURCHASE PLAN.
 
                                       83
<PAGE>
              SECURITY OWNERSHIP OF OCCUSYSTEMS, CRA AND CONCENTRA
 
OCCUSYSTEMS
 
    The following table sets forth the beneficial ownership of OccuSystems
Common Stock, as of April 30, 1997, of each person who is (i) an OccuSystems
director, (ii) the Chief Executive Officer of OccuSystems, (iii) the four most
highly compensated executive officers of OccuSystems other than the Chief
Executive Officer, calculated based upon the compensation of the executive
officers of OccuSystems for 1996, (iv) all OccuSystems directors and executive
officers, as a group, or (v) a beneficial owner of five percent or more of the
outstanding OccuSystems Common Stock.
 
<TABLE>
<CAPTION>
                                                                                               BENEFICIAL OWNERSHIP
                                                                                              -----------------------
<S>                                                                                           <C>         <C>
                                                                                              NUMBER OF
NAME AND ADDRESS OF BENEFICIAL OWNER                                                          SHARES (1)    PERCENT
- --------------------------------------------------------------------------------------------  ----------  -----------
Richard D. Rehm, M.D........................................................................     305,438         1.4%
Daniel J. Thomas............................................................................     200,367           *
John K. Carlyle.............................................................................     152,250           *
W. Thomas Fogarty, M.D......................................................................     128,864           *
James M. Greenwood..........................................................................      41,250           *
Robert A. Ortenzio(2).......................................................................      26,719           *
Paul B. Queally.............................................................................      10,799           *
Robert W. O'Leary...........................................................................       5,000           *
Richard A. Parr II..........................................................................          --           *
Stephen A. George, M.D......................................................................          --           *
Putnam Investments, Inc.(3).................................................................   2,373,981        11.0
  One Post Office Square
  Boston, Massachusetts 02109
Pilgrim, Baxter & Assoc.(3).................................................................   1,446,321         6.7
  1255 Drummers Lane, Suite 300
  Wayne, Pennsylvania 19087
All directors and executive officers as a group (10 persons)................................     870,687         4.0%
</TABLE>
 
- ------------------------
 
*   Less than one percent
 
(1) Includes shares of OccuSystems Common Stock which an individual has a right
    to acquire upon exercise of options or warrants or conversion of debt
    securities within 60 days of March 31, 1997. Such shares are deemed to be
    outstanding for purposes of computing the percentage ownership of the
    individual holding such shares, but are not deemed outstanding for purposes
    of computing the percentage of any other person shown on the table.
 
(2) Includes 5,000 shares held of record by Remainderman Life Estate, which Mr.
    Ortenzio indirectly owns.
 
(3) Ownership is based upon a Schedule 13G filed on or before March 10, 1997.
 
                                       84
<PAGE>
CRA
 
    The following table sets forth the beneficial ownership of CRA Common Stock,
as of April 30, 1997, of each person who is (i) a CRA director, (ii) the Chief
Executive Officer of CRA, (iii) the four most highly compensated executive
officers of CRA other than the Chief Executive Officer, calculated based upon
the compensation of the executive officers of CRA for 1996, (iv) all CRA
directors and executive officers, as a group, or (v) a beneficial owner of five
percent or more of the outstanding CRA Common Stock.
 
<TABLE>
<CAPTION>
                                                                                               BENEFICIAL OWNERSHIP
                                                                                              -----------------------
<S>                                                                                           <C>         <C>
                                                                                              NUMBER OF
NAME AND ADDRESS OF BENEFICIAL OWNER                                                          SHARES (1)    PERCENT
- --------------------------------------------------------------------------------------------  ----------  -----------
Donald J. Larson(2).........................................................................     948,148        10.6%
Lois E. Silverman(3)........................................................................     433,647         4.8
George H. Conrades..........................................................................      23,500           *
Mitchell T. Rabkin, M.D.....................................................................      15,866           *
Jeffrey R. Jay, M.D.........................................................................          --           *
Anne E. Kirby...............................................................................      13,882           *
Peter R. Gates..............................................................................      10,000           *
Joseph F. Pesce.............................................................................       2,304           *
John A. McCarthy, Jr........................................................................          --          --
Putnam Investment Management, Inc.(4).......................................................   1,204,300        13.4
  The Putnam Advisory Company, Inc.
  One Post Office Square
  Boston, Massachusetts 02109
Arlene Osoff, Trustee(5)....................................................................     485,323         5.4
  c/o Jansson
  411 Waverly Oak Drive
  Waltham, Massachusetts 02154
All directors and executive officers as a group (9 persons).................................   1,447,347        16.1%
</TABLE>
 
- ------------------------
 
*   Less than one percent
 
(1) Includes shares of CRA Common Stock which an individual has a right to
    acquire upon exercise of options or warrants or conversion of debt
    securities within 60 days of April 30, 1997. Such shares are deemed to be
    outstanding for purposes of computing the percentage ownership of the
    individual holding such shares, but are not deemed outstanding for purposes
    of computing the percentage of any other person shown on the table.
 
(2) Includes 18,750 shares of CRA Common Stock held of record by trusts created
    for the benefit of Mr. Larson's children.
 
(3) Includes 23,500 shares of CRA Common Stock held of record by the Michael E.
    Silverman 1996 Irrevocable Trust dated March 13, 1995 (the "Michael
    Silverman Trust"), 23,500 shares of CRA Common Stock held of record by the
    Susan E. Bender 1995 Irrevocable Trust dated March 13, 1995 (the "Susan
    Bender Trust"), and 28,500 shares of CRA Common Stock held in the Silverman
    Family Foundation, Inc. Ms. Silverman disclaims beneficial ownership of the
    shares held by such trusts and such foundation.
 
(4) Ownership is based upon a Schedule 13G filed on or before March 10, 1997.
 
(5) Consists of 438,323 shares of CRA Common Stock held of record by the
    Silverman 1996 Grantor Retained Annuity Trust, 23,500 shares of CRA Common
    Stock held of record by the Michael Silverman Trust and 23,500 shares of CRA
    Common Stock held of record by the Susan Bender Trust.
 
                                       85
<PAGE>
CONCENTRA
 
    The following table sets forth the anticipated beneficial ownership of
Concentra Common Stock, after giving effect to the Mergers, of each person
expected to be (i) a Concentra director, (ii) the Chief Executive Officer of
Concentra, (iii) the four most highly compensated executive officers of
Concentra other than the Chief Executive Officer, calculated based upon the
compensation of the executive officers of OccuSystems and CRA for 1996, (iv) all
persons expected to be Concentra directors and executive officers, as a group,
or (v) a beneficial owner of five percent or more of the outstanding CRA Common
Stock.
 
<TABLE>
<CAPTION>
                                                                                               BENEFICIAL OWNERSHIP
                                                                                              -----------------------
<S>                                                                                           <C>         <C>
                                                                                              NUMBER OF
NAME AND ADDRESS OF BENEFICIAL OWNER                                                          SHARES (1)    PERCENT
- --------------------------------------------------------------------------------------------  ----------  -----------
 
Donald J. Larson(2).........................................................................   1,694,392         4.5%
Lois E. Silverman(3)........................................................................     774,493         2.1
John K. Carlyle.............................................................................     277,250           *
Daniel J. Thomas............................................................................     275,367           *
W. Thomas Fogarty, M.D......................................................................     159,689           *
George H. Conrades..........................................................................      41,971           *
Mitchell T. Rabkin, M.D.....................................................................      28,336           *
Robert A. Ortenzio(4).......................................................................      26,719           *
Paul B. Queally.............................................................................      10,799           *
Robert W. O'Leary...........................................................................       5,000           *
Joseph F. Pesce.............................................................................       4,114           *
John A. McCarthy, Jr........................................................................       1,000          --
Putnam Investment Management, Inc.(5).......................................................   4,524,860        12.0
  The Putnam Advisory Company, Inc.
  One Post Office Square
  Boston, Massachusetts 02109
All directors and executive officers as a group (15 persons)................................   3,464,490         9.2%
</TABLE>
 
- ------------------------
 
*   Less than one percent
 
(1) Includes shares of Concentra Common Stock which an individual has a right to
    acquire upon exercise of options or warrants or conversion of debt
    securities within 60 days of April 30, 1997, including giving effect to the
    acceleration of stock options resulting from the Mergers. Such shares are
    deemed to be outstanding for purposes of computing the percentage ownership
    of the individual holding such shares, but are not deemed outstanding for
    purposes of computing the percentage of any other person shown on the table.
 
(2) Includes 33,488 shares of Common Stock held of record by trusts created for
    the benefit of Mr. Larson's children.
 
(3) Includes 41,971 shares of Common Stock held of record by the Michael E.
    Silverman 1996 Irrevocable Trust dated March 13, 1995 (the "Michael
    Silverman Trust"), 41,971 shares of CRA Common Stock held of record by the
    Susan E. Bender 1995 Irrevocable Trust dated March 13, 1995 (the "Susan
    Bender Trust"), and 50,901 shares of Common Stock held in the Silverman
    Family Foundation, Inc. Ms. Silverman disclaims beneficial ownership of the
    shares held by such trusts and such foundation.
 
(4) Includes 5,000 shares held of record by Remainderman Life Estate, which Mr.
    Ortenzio indirectly owns.
 
(5) Ownership is based upon a Schedule 13G filed on or before March 10, 1997.
 
                                       86
<PAGE>
                                 LEGAL MATTERS
 
    The validity of the Concentra Common Stock to be issued in connection with
the Mergers will be passed upon by Vinson & Elkins L.L.P. The federal income tax
consequences in connection with the OccuSystems Merger will be passed upon for
OccuSystems and Concentra by Vinson & Elkins L.L.P. The federal income tax
consequences in connection with the CRA Merger will be passed upon for CRA by
Hutchins, Wheeler & Dittmar, A Professional Corporation.
 
                                    EXPERTS
 
    The consolidated financial statements of OccuSystems as of December 31, 1996
and 1995 and for each of the three years in the period ended December 31, 1996,
incorporated in this Joint Proxy Statement/ Prospectus by reference to the
OccuSystems Form 10-K, have been so incorporated in reliance on the report of
Arthur Andersen LLP, independent public accountants, given on the authority of
said firm as experts in auditing and accounting.
 
    The consolidated financial statements of CRA at December 31, 1996 and 1995
and for each of the three years in the period ended December 31, 1996,
incorporated by reference in this Joint Proxy Statement/Prospectus by reference
to the CRA Form 10-K, have been so incorporated in reliance on the report of
Arthur Andersen LLP, independent public accountants, given upon the authority of
such firm as experts in accounting and auditing.
 
    It is expected that representatives of Arthur Andersen LLP, OccuSystems' and
CRA's independent public accountants, will be present at the OccuSystems Meeting
and at the CRA Meeting where they will have an opportunity to respond to
appropriate questions of stockholders and to make a statement if they so desire.
 
                          FUTURE STOCKHOLDER PROPOSALS
 
    If the Mergers are consummated, the first annual meeting of the public
stockholders of Concentra after such consummation is expected to be held May   ,
1998.
 
    Subject to the foregoing, if any Concentra stockholder intends to present a
proposal at the 1998 Concentra annual meeting and wishes to have such proposal
considered for inclusion in the proxy materials for such meeting, such holder
must submit the proposal to the Secretary of Concentra in writing so as to be
received at the executive offices of Concentra by       , 1998. Such proposals
must also meet the other requirements of the rules of the Commission relating to
stockholders' proposals.
 
                                       87
<PAGE>
                                                                      APPENDIX A
 
                            ------------------------
 
                      AGREEMENT AND PLAN OF REORGANIZATION
                                     AMONG
                             CRA MANAGED CARE, INC.
                               OCCUSYSTEMS, INC.
                                      AND
                          CONCENTRA MANAGED CARE, INC.
                                 APRIL 21, 1997
                               ------------------
<PAGE>
                               TABLE OF CONTENTS
 
<TABLE>
<CAPTION>
                                                                                                                 PAGE
                                                                                                               ---------
<S>         <C>                                                                                                <C>
ARTICLE I
            FORMATION OF HOLDING COMPANY AND SUBSIDIARIES....................................................          1
            1.1. Holding Company.............................................................................          1
            1.2. Directors and Officers of Holding Company...................................................          2
            1.3. Organization of CRA Merger Subsidiary.......................................................          2
            1.4. Actions of Directors and Officers...........................................................          2
            1.5. Actions of CRA and OSI......................................................................          2
 
ARTICLE 2
            THE MERGERS; CLOSING.............................................................................          2
            2.1. The Mergers.................................................................................          2
            2.2. The Closing.................................................................................          3
 
ARTICLE 3
            DIRECTORS AND OFFICERS OF CRA MERGER SUB AND SURVIVING CORPORATIONS..............................          3
            3.1. Directors...................................................................................          3
            3.2. Officers....................................................................................          3
 
ARTICLE 4
            EFFECT OF THE MERGERS ON SECURITIES OF CRA, OSI, HOLDING COMPANY AND THE CRA MERGER SUB..........          3
            4.1. CRA Merger Sub Stock........................................................................          3
            4.2. Holding Company Capital Stock...............................................................          3
            4.3. Conversion of CRA Stock.....................................................................          3
            4.4. Conversion of OSI Common Stock..............................................................          5
            4.5. Fractional Shares, Etc......................................................................          5
            4.6. Exchange Fund Exchange Procedures, Etc......................................................          6
 
ARTICLE 5
            REPRESENTATIONS AND WARRANTIES OF OSI............................................................          8
            5.1.  Existence; Good Standing; Corporate Authority..............................................          8
            5.2.  Authorization, Validity and Effect of Agreements...........................................          8
            5.3.  Capitalization.............................................................................          8
            5.4.  Subsidiaries...............................................................................          9
            5.5.  Other Interests............................................................................          9
            5.6.  No Conflict; Required Filings and Consents.................................................          9
            5.7.  Compliance.................................................................................         10
            5.8.  SEC Documents..............................................................................         10
            5.9.  Litigation.................................................................................         11
            5.10. Absence of Certain Changes.................................................................         11
            5.11. Taxes......................................................................................         11
            5.12. Employee Benefit Plans.....................................................................         12
            5.13. Labor Matters..............................................................................         13
            5.14. No Brokers.................................................................................         13
            5.15. Opinion of Financial Advisor...............................................................         13
            5.16. Preliminary Pooling Letter.................................................................         13
</TABLE>
 
                                       i
<PAGE>
<TABLE>
<CAPTION>
                                                                                                                 PAGE
                                                                                                               ---------
<S>         <C>                                                                                                <C>
ARTICLE 6
            REPRESENTATIONS AND WARRANTIES OF CRA............................................................         13
            6.1.  Existence; Good Standing; Corporate Authority..............................................         13
            6.2.  Authorization, Validity and Effect of Agreements...........................................         14
            6.3.  Capitalization.............................................................................         14
            6.4.  Subsidiaries...............................................................................         14
            6.5.  Other Interests............................................................................         15
            6.6.  No Conflict; Required Filings and Consents.................................................         15
            6.7.  Compliance.................................................................................         16
            6.8.  SEC Documents..............................................................................         16
            6.9.  Litigation.................................................................................         16
            6.10. Absence of Certain Changes.................................................................         16
            6.11. Taxes......................................................................................         17
            6.12. Employee Benefit Plans.....................................................................         17
            6.13. Labor Matters..............................................................................         18
            6.14. No Brokers.................................................................................         18
            6.15. Opinion of Financial Advisor...............................................................         19
            6.16. Preliminary Pooling Letter.................................................................         19
 
ARTICLE 7
            COVENANTS........................................................................................         19
            7.1.  Alternative Proposals......................................................................         19
            7.2.  Interim Operations.........................................................................         21
            7.3.  Meetings of Stockholders...................................................................         24
            7.4.  Filings, Other Action......................................................................         24
            7.5.  Inspection of Records......................................................................         25
            7.6.  Publicity..................................................................................         25
            7.7.  Registration Statement.....................................................................         25
            7.8.  Listing Application........................................................................         26
            7.9.  Further Action.............................................................................         26
            7.10. Affiliate Letters..........................................................................         26
            7.11. Expenses...................................................................................         27
            7.12. Insurance; Indemnity.......................................................................         27
            7.13. Takeover Statute...........................................................................         28
            7.14. Conduct of Business by Holding Company and CRA Merger Sub Pending the
            Mergers..........................................................................................         28
            7.15. Employee Benefits..........................................................................         28
            7.16. Conveyance Taxes...........................................................................         28
            7.17. Incentive Plan.............................................................................         28
 
ARTICLE 8
            CONDITIONS.......................................................................................         29
            8.1. Conditions to Each Party's Obligation to Effect the Mergers.................................         29
            8.2. Conditions to Obligation of OSI to Effect the Mergers.......................................         29
            8.3. Conditions to Obligation of CRA to Effect the Mergers.......................................         30
</TABLE>
 
                                       ii
<PAGE>
<TABLE>
<CAPTION>
                                                                                                                 PAGE
                                                                                                               ---------
<S>         <C>                                                                                                <C>
ARTICLE 9
            TERMINATION......................................................................................         31
            9.1. Termination by Mutual Consent...............................................................         31
            9.2. Termination by Either CRA or OSI............................................................         31
            9.3. Termination by OSI..........................................................................         31
            9.4. Termination by CRA..........................................................................         31
            9.5. Effect of Termination and Abandonment.......................................................         32
            9.6. Extension, Waiver...........................................................................         32
 
ARTICLE 10
            GENERAL PROVISIONS...............................................................................         33
            10.1.  Nonsurvival of Representations, Warranties and Agreements.................................         33
            10.2.  Notices...................................................................................         33
            10.3.  Assignment; Binding Effect................................................................         34
            10.4.  Entire Agreement..........................................................................         34
            10.5.  Amendment.................................................................................         34
            10.6.  Governing Law.............................................................................         34
            10.7.  Counterparts..............................................................................         34
            10.8.  Headings..................................................................................         35
            10.9.  Interpretation............................................................................         35
            10.10. Waivers...................................................................................         35
            10.11. Incorporation of Exhibits.................................................................         35
            10.12. Severability..............................................................................         35
            10.13. Enforcement of Agreement..................................................................         35
            10.14. Subsidiaries..............................................................................         35
</TABLE>
 
                                      iii
<PAGE>
                      AGREEMENT AND PLAN OF REORGANIZATION
 
    AGREEMENT AND PLAN OF REORGANIZATION (this "Agreement"), dated as of April
21, 1997, among CRA Managed Care, Inc., a Massachusetts corporation ("CRA"),
OccuSystems, Inc., a Delaware corporation ("OSI"), and Concentra Managed Care,
Inc., a Delaware corporation ("Holding Company").
 
                                    RECITALS
 
    A. The Boards of Directors of CRA, OSI and Holding Company have approved,
and deem it advisable and in the best interests of their respective companies
and stockholders, to consummate the reorganization (the "Reorganization")
provided for herein, pursuant to which (i) Holding Company will acquire all of
the common stock of CRA through the merger of a Subsidiary (as defined in
Section 10.14) of Holding Company with and into CRA and (ii) OSI will be merged
with and into Holding Company.
 
    B. For federal income tax purposes, it is intended that the CRA Merger (as
hereinafter defined) will qualify as an exchange under the provisions of Section
351 of the United States Internal Revenue Code of 1986, as amended (the "Code"),
a tax free reorganization under Section 368(a) of the Code or both, and that the
OSI Merger (as hereafter defined) will qualify as a tax free reorganization
under Section 368(a) of the Code.
 
    C. CRA and OSI desire to make certain representations, warranties, covenants
and agreements in connection with the transactions contemplated hereby.
 
    D. Simultaneously with the execution and delivery of this Agreement CRA has
entered into a certain CRA Managed Care, Inc. Stock Option Agreement (the "CRA
Stock Option Agreement) pursuant to which OSI has the right to acquire certain
shares of CRA Common Stock subject to and in accordance with the terms and
conditions of said Agreement and simultaneously with the execution and delivery
of this Agreement OSI has entered into a certain OccuSystems, Inc. Stock Option
Agreement (the "OSI Stock Option Agreement") pursuant to which CRA has the right
to acquire certain shares of OSI Common Stock subject to and in accordance with
the terms and conditions of said Agreement.
 
    NOW, THEREFORE, in consideration of the foregoing, and of the
representations, warranties, covenants and agreements contained herein, the
parties hereto hereby agree as follows:
 
                                   ARTICLE I
 
                 FORMATION OF HOLDING COMPANY AND SUBSIDIARIES
 
    1.1. HOLDING COMPANY. Holding Company is a corporation newly formed for the
purpose of entering into this Agreement and effecting the transactions
contemplated hereby. Holding Company has undertaken no actions and has incurred
no liabilities other than in connection with this Agreement and the transactions
contemplated hereby. The Certificate of Incorporation and By-laws of Holding
Company are set forth on Exhibit A attached hereto. The Certificate of
Incorporation of Holding Company will be amended prior to the Effective Time to
provide that (a) the authorized capital stock of Holding Company shall consist
of 100,000,000 shares of common stock, $.01 par value (the "Holding Company
Common Stock") and 20,000,000 shares of blank check preferred stock, $.01 par
value, (b) Holding Company shall have a staggered board of directors, (c) no
action required to be taken or that may be taken at any meeting of common
stockholders of Holding Company may be taken without a meeting, and the power of
common stockholders to consent in writing, without a meeting, to the taking of
any action is specifically denied, and (d) special meetings of the stockholders
of Holding Company, and any proposals to be considered at such meetings, may be
called and proposed exclusively by Holding Company's Board of Directors, and the
stockholders of Holding Company shall not have the right to call special
meetings of the stockholders or to propose business at a special meeting thereof
(in each of cases (b), (c) and (d), on terms substantially similar to the forms
of such provisions previously reviewed by the parties hereto). Immediately prior
to the Effective Time there shall be no more than 100 shares of Holding Company
Common Stock outstanding.
 
                                      A-1
<PAGE>
    1.2. DIRECTORS AND OFFICERS OF HOLDING COMPANY. Immediately following the
execution and delivery of this Agreement the directors and officers of Holding
Company shall be as set forth on Schedule 1.2 attached hereto. Each such officer
and director shall remain in office until his or her successors are elected.
 
    1.3. ORGANIZATION OF CRA MERGER SUBSIDIARY. As promptly as practicable
following the execution of this Agreement, Holding Company shall cause CRA
Merger Corp., a corporation organized under the laws of the Commonwealth of
Massachusetts ("CRA Merger Sub") to be organized for the sole purpose of
effectuating the CRA Merger contemplated herein. The Articles of Organization
and By-laws of CRA Merger Sub are and at Closing shall be substantially in the
forms attached hereto as Exhibit B. The authorized capital stock of CRA Merger
Sub are and shall at Closing consist of 100 shares of common stock, par value
$.01 per share, all of which are and at Closing shall be owned by Holding
Company.
 
    1.4. ACTIONS OF DIRECTORS AND OFFICERS. As promptly as practicable following
the execution of this Agreement, Holding Company shall cause (a) the directors
of CRA Merger Sub to ratify and approve the Merger Agreement (as defined in
Section 2.1) to be executed on behalf of the CRA Merger Sub, and (b) the
directors and officers of the CRA Merger Sub to take such steps as may be
necessary or appropriate to complete the organization of the CRA Merger Sub and
to approve the Merger Agreement (as defined in Section 2.1).
 
    1.5. ACTIONS OF CRA AND OSI. CRA and OSI, as the holders of all of the
outstanding shares of capital stock of Holding Company, have ratified and
approved this Agreement, and Holding Company, as the sole shareholder of CRA
Merger Sub, has ratified and approved the Merger Agreement. CRA, OSI and Holding
Company agree that they shall not rescind, revoke, condition or impair any such
ratification or approval. CRA and OSI shall cause Holding Company and CRA Merger
Sub to perform their respective obligations under this Agreement and the Merger
Agreements.
 
                                   ARTICLE 2
 
                              THE MERGERS; CLOSING
 
    2.1. THE MERGERS. Pursuant to Plans of Merger substantially in the forms
attached as Exhibits C and D (sometimes hereinafter referred to individually as
the "CRA Merger Agreement" and the "OSI Merger Agreement", respectively, and
collectively as the "Merger Agreements"), upon the terms and subject to the
conditions set forth in this Agreement and in the Merger Agreements:
 
        (a) CRA Merger Sub shall be merged with and into CRA (the "CRA Merger")
    in accordance with the applicable provisions of the laws of the Commonwealth
    of Massachusetts. CRA shall be the surviving corporation in the CRA Merger
    and shall continue its corporate existence under the laws of the
    Commonwealth of Massachusetts. As a result of the CRA Merger, CRA shall
    become a wholly owned Subsidiary of Holding Company. The effects and
    consequences of the CRA Merger shall be as set forth in the CRA Merger
    Agreement and as provided by the laws of the Commonwealth of Massachusetts.
 
        (b) OSI will be merged with and into Holding Company (the "OSI Merger"),
    in accordance with the applicable provisions of the laws of the State of
    Delaware. Holding Company shall be the surviving corporation in the OSI
    Merger and shall continue its corporate existence under the laws of the
    State of Delaware. The effects and consequences of the OSI Merger shall be
    as set forth in the OSI Merger Agreement and as provided by the laws of the
    State of Delaware. The term "Mergers" shall mean the CRA Merger and the OSI
    Merger.
 
        (c) The term "Effective Time" shall mean the time and date which is (A)
    the later of (i) the date and time of the filing of the articles of merger
    relating to the CRA Merger with the Secretary of State of the Commonwealth
    of Massachusetts (or such other date and time as may be specified in such
    certificate as may be permitted by law) and (ii) the date and time of the
    filing of a certificate of merger
 
                                      A-2
<PAGE>
    with the Secretary of State of the State of Delaware with respect to the OSI
    Merger (or such other date and time as may be specified in such certificate
    as may be permitted by law) or (B) such other time and date as CRA and OSI
    may agree.
 
    2.2. THE CLOSING. Subject to the terms and conditions of this Agreement, the
closing of the transactions contemplated by this Agreement and the Merger
Agreements (the "Closing") shall take place (a) at the offices of Hutchins,
Wheeler & Dittmar, A Professional Corporation, Boston, Massachusetts at 10:00
a.m., local time, on the third business day following the day on which the last
to be fulfilled or waived of the conditions set forth in Article 8 shall be
fulfilled or waived in accordance herewith or (b) at such other time, date or
place as CRA and OSI may agree. The date on which the Closing occurs is
hereinafter referred to as the "Closing Date."
 
                                   ARTICLE 3
 
                    DIRECTORS AND OFFICERS OF CRA MERGER SUB
                           AND SURVIVING CORPORATIONS
 
    3.1. DIRECTORS. The persons listed on Schedule 3.1(a) shall be the directors
of the surviving corporation of the CRA Merger as of the Effective Time and
until their successors are duly appointed or elected in accordance with
applicable law. The directors of the surviving corporation of the OSI Merger as
of the Effective Time shall include four (4) individuals appointed by CRA and
four (4) individuals appointed by OSI. The persons listed on Schedule 3.1(b)
shall be the directors of OccuCenters, Inc. ("OCI"), a wholly owned subsidiary
of Holding Company, as of the Effective Time and until their successors are duly
appointed or elected in accordance with applicable law. The Board of Directors
of the surviving corporation of the OSI Merger as of the Effective Time shall
establish the following committees: (i) a Compensation Committee consisting of
three (3) members including one independent director; (ii) an Audit Committee
consisting of two (2) members; and (iii) a Nominating Committee consisting of
two (2) members.
 
    3.2. OFFICERS. The persons listed on Schedules 3.2(a) and 3.2(b) shall be
the officers of the surviving corporations of the CRA Merger and the OSI Merger,
respectively, as of the Effective Time and until their successors are duly
appointed or elected in accordance with applicable law. The persons listed on
Schedule 3.2(c) shall be the officers of OCI as of the Effective Time and until
their successors are duly appointed or elected in accordance with applicable
law.
 
                                   ARTICLE 4
 
                     EFFECT OF THE MERGERS ON SECURITIES OF
                       CRA, OSI, HOLDING COMPANY AND THE
                                 CRA MERGER SUB
 
    4.1. CRA MERGER SUB STOCK. At the Effective Time, each share of the common
stock of CRA Merger Sub outstanding immediately prior to the Effective Time
shall be converted into and shall become one share of common stock of the
surviving corporation of the CRA Merger.
 
    4.2. HOLDING COMPANY CAPITAL STOCK. At the Effective Time, each share of the
capital stock of Holding Company issued and outstanding immediately prior to the
Effective Time shall be canceled and retired without payment of any
consideration therefor.
 
    4.3. CONVERSION OF CRA STOCK. (a) Subject to Section 4.3(b), at the
Effective Time, each share of common stock, par value $0.01 per share, of CRA
("CRA Common Stock") issued and outstanding at the Effective Time shall be
converted into the right to receive 1.786 (the "CRA Ratio") shares of Holding
Company Common Stock, payable upon the surrender of the certificates formerly
representing CRA Common Stock pursuant to Section 4.6.
 
                                      A-3
<PAGE>
    (b) As a result of the CRA Merger and without any action on the part of the
holder thereof, at the Effective Time all shares of CRA Common Stock shall cease
to be outstanding and shall be canceled and retired and shall cease to exist,
and each holder of shares of CRA Common Stock shall thereafter cease to have any
rights with respect to such shares of CRA Common Stock, except the right to
receive the number of shares of Holding Company Common Stock determined in
accordance with Section 4.3(a), cash without interest, for fractional shares of
Holding Company Common Stock in accordance with Section 4.5 and dividends or
other distributions, if any, in accordance with Section 4.5 upon the surrender
of a certificate representing such shares of CRA Common Stock (a "CRA
Certificate").
 
    (c) At the Effective Time, each share of CRA Common Stock which is held in
the treasury of CRA immediately prior to the Effective Time shall, by virtue of
the Mergers, cease to be outstanding and shall be canceled and retired without
payment of any consideration therefor.
 
    (d) Notwithstanding anything in this Section 4.3 to the contrary, shares of
CRA Common Stock which are issued and outstanding immediately prior to the
Effective Time and which are held by stockholders who have not voted such shares
in favor of the CRA Merger and who shall have properly exercised their rights of
appraisal for such shares in the manner provided by the Massachusetts General
Business Corporation Law, Chapter 156B (the "MBCL") (the "CRA Dissenting
Shares"), shall not be converted into the right to receive the Holding Company
Common Stock, unless and until such holder shall have failed to perfect or shall
have effectively withdrawn or lost his right to appraisal and payment, as the
case may be. If such holder shall have so failed to perfect or shall have
effectively withdrawn or lost such right, his shares shall thereupon be deemed
to have been converted into, at the Effective Time, the right to receive the
Holding Company Common Stock plus cash in accordance with Section 4.5 and
Section 4.6. CRA shall give OSI prompt notice of any CRA Dissenting Shares (and
shall also give OSI prompt notice of any withdrawals of such demands for
appraisal rights) and Holding Company shall have the right to direct all
negotiations and proceedings with respect to any such demands. Neither CRA nor
the surviving corporation of the CRA Merger shall, except with the prior written
consent of Holding Company, voluntarily make any payment with respect to, or
settle or offer to settle, any such demand for appraisal rights.
 
    (e) At the Effective Time, each outstanding option or right to purchase
shares of CRA Common Stock (a "CRA Option") shall be assumed by Holding Company
in such manner that it is converted into an option to purchase shares of Holding
Company Common Stock, as provided below. Following the Effective Time, each such
CRA Option shall be exercisable upon the same terms and conditions as then are
applicable to such CRA Option, except that (i) each such CRA Option shall be
exercisable for that number of shares of Holding Company Common Stock equal to
the product of (x) the number of shares of CRA Common Stock for which such CRA
Option was exercisable and (y) the CRA Ratio and (ii) the exercise price of such
option shall be equal to the exercise price of such option as of the date hereof
divided by the CRA Ratio. It is the intention of the parties that, to the extent
that any such CRA Option constituted an "incentive stock option" (within the
meaning of Section 422 of the Code) immediately prior to the Effective Time,
such option continue to qualify as an incentive stock option to the maximum
extent permitted by Section 422 of the Code, and that the assumption of CRA
Stock Options provided by this Section 4.3(e) satisfy the conditions of Section
424(a) of the Code. From and after the date of this Agreement, no additional
options to purchase shares of CRA Common Stock shall be granted under the CRA
1994 Time Accelerated Restricted Stock Option Plan, the CRA 1994 Non-Qualified
Stock Option Plan for Non-Employee Directors, the CRA 1997 Stock Option Plan or
any other CRA option, stock or other benefit plan or agreement (collectively,
the "CRA Stock Option Plans") (other than (i) the grant of options to
individuals other than executive officers of CRA to acquire up to 15,000 shares
of CRA Common Stock pursuant to the terms of the CRA Stock Option Plans at an
exercise price of not less than the fair market value of the CRA Common Stock on
the date of grant and (ii) the option granted to OSI on the date hereof).
 
                                      A-4
<PAGE>
    4.4. CONVERSION OF OSI COMMON STOCK. (a) Subject to Sections 4.4(c) and
4.4(d), at the Effective Time each issued and outstanding share of Common Stock,
$.01 par value of OSI (the "OSI Common Stock"), shall be converted into the
right to receive one (the "OSI Ratio") share of Holding Company Common Stock,
payable upon the surrender of the certificates formerly representing OSI Common
Stock pursuant to Section 4.6.
 
    (b) As a result of the OSI Merger and without any action on the part of the
holders thereof, at the Effective Time all shares of OSI Common Stock shall
cease to be outstanding and shall be canceled and retired and shall cease to
exist, and each holder of shares of OSI Common Stock shall thereafter cease to
have any rights with respect to such shares of OSI Common Stock, except the
right to receive the number of shares of Holding Company Common Stock determined
in accordance with Section 4.4(a), cash, without interest, for fractional shares
of Holding Company Common Stock in accordance with Section 4.5 and dividends or
other distributions, if any, in accordance with Section 4.5 upon the surrender
of a certificate representing such shares of OSI Common Stock (an "OSI
Certificate").
 
    (c) Notwithstanding anything contained in this Section 4.4 to the contrary,
each share of OSI Common Stock issued and held in OSI's treasury immediately
prior to the Effective Time shall, by virtue of the OSI Merger, cease to be
outstanding and shall be canceled and retired without payment of any
consideration therefor.
 
    (d) At the Effective Time, each outstanding option or right to purchase
shares of OSI Common Stock (a "OSI Option") shall be assumed by Holding Company
in such manner that it is converted into an option to purchase shares of Holding
Company Common Stock, as provided below. Following the Effective Time, each such
OSI Option shall be exercisable upon the same terms and conditions as then are
applicable to such OSI Option, except that (i) each such OSI Option shall be
exercisable for that number of shares of Holding Company Common Stock equal to
the product of (x) the number of shares of OSI Common Stock for which such OSI
Option was exercisable and (y) the OSI Ratio and (ii) the exercise price of such
option shall be equal to the exercise price of such option as of the date hereof
divided by the OSI Ratio. It is the intention of the parties that, to the extent
that any such OSI Option constituted an "incentive stock option" (within the
meaning of Section 422 of the Code) immediately prior to the Effective Time,
such option continue to qualify as an incentive stock option to the maximum
extent permitted by Section 422 of the Code, and that the assumption of OSI
Options provided by this Section 4.4(d) satisfy the conditions of Section 424(a)
of the Code. From and after the date of this Agreement, no additional options to
purchase shares of OSI Common Stock shall be granted under the OSI 1995
Long-Term Incentive Plan, the First Amended and Restated OSI and its
Subsidiaries and Affiliates Stock Option and Restricted Stock Purchase Plan, the
currently existing stock option agreements of OSI not governed by such plans or
any other OSI option, stock or other benefit plan or agreement (collectively,
the "OSI Stock Option Plans") (other than (i) the grant of options to
individuals other than executive officers of OSI to acquire up to 15,000 shares
of OSI Common Stock pursuant to the terms of the OSI Stock Option Plans at an
exercise price of not less than fair market value of the OSI Common Stock on the
date of grant and (ii) the option granted to CRA on the date hereof).
 
    4.5. FRACTIONAL SHARES, ETC. No certificate or scrip representing fractional
shares of Holding Company Common Stock shall be issued upon the surrender for
exchange of Certificates (as hereinafter defined) except pursuant to this
Section 4.5, no dividend or other distribution, stock split or interest shall
relate to any such fractional shares, and such fractional shares shall not
entitle the holder thereof to vote or to any rights of a security holder of
Holding Company. In lieu of any fractional shares, each holder of shares of
Converted Stock (as hereinafter defined) who would otherwise have been entitled
to a fraction of a share of Holding Company Common Stock upon surrender of
Certificates for exchange pursuant to this Article 4 will be paid an amount of
cash (without interest) equal to such holder's proportionate interest in the sum
of (i) the gross proceeds from the sale or sales by the Exchange Agent (as
hereinafter defined) in accordance with the provisions of this Section 4.5, on
behalf of all such holders of shares of Converted Stock, of the aggregate
fractional shares of Holding Company Common Stock issued pursuant to this
 
                                      A-5
<PAGE>
Article 4 and (ii) the aggregate dividends or other distributions that are
payable to holders of shares of Converted Stock with respect to such shares of
Holding Company Common Stock pursuant to Section 4.6(c) (such dividends and
distributions being herein called the "Fractional Dividends"). As soon as
practicable following the Effective Time, the Exchange Agent shall determine the
excess of (x) the number of full shares of Holding Company Common Stock
delivered to the Exchange Agent by Holding Company pursuant to Section 4.6(a)
over (y) the aggregate number of full shares of Holding Company Common Stock to
be distributed to the holders of Converted Stock pursuant to Section 4.3 (with
respect to CRA Common Stock) and Section 4.4 (with respect to OSI Common Stock)
(such excess being herein called the "Excess Securities") and the Exchange
Agent, as agent for the former holders of Converted Stock, shall sell the Excess
Securities at the prevailing prices on the Nasdaq National Market. The sale of
the Excess Securities by the Exchange Agent shall be executed on the Nasdaq
National Market through one or more member firms of the National Association of
Securities Dealers, Inc. Holding Company shall pay all commissions, transfer
taxes and other out-of-pocket transaction costs, including the expenses and
compensation of the Exchange Agent, incurred in connection with such sale of
Excess Securities. Until the gross proceeds of such sale of Excess Securities
and the Fractional Dividends, if any, have been distributed to the former
holders of shares of Converted Stock, the Exchange Agent will hold such proceeds
and dividends in trust for such former holders.
 
    4.6 EXCHANGE FUND EXCHANGE PROCEDURES, ETC. (a) At or prior to the Effective
Time, Holding Company shall deposit, or cause to be deposited, with a bank or
trust company designated by Holding Company (the "Exchange Agent"), for the
benefit of the holders of CRA Common Stock and OSI Common Stock which were
outstanding immediately prior to the Effective Time, for exchange in accordance
with this Section 4.6, through the Exchange Agent, (i) certificates evidencing a
number of shares of Holding Company Common Stock equal to the aggregate number
issuable to holders of CRA Common Stock pursuant to Section 4.3, together with
any dividend or distribution with respect thereto and (ii) certificates
evidencing a number of shares of Holding Company Common Stock equal to the
aggregate number issuable to holders of OSI Common Stock pursuant to Section
4.4, together with any dividend or distribution with respect thereto. The
certificates and cash deposited with the Exchange Agent in accordance with this
subsection 4.6(a) are hereinafter referred to as the "Exchange Fund." The
Exchange Agent shall, pursuant to irrevocable instructions, deliver Holding
Company Common Stock and cash, as described above, in exchange for surrendered
certificates representing CRA Common Stock and OSI Common Stock pursuant to the
terms of this Agreement out of the Exchange Fund.
 
    (b) As soon as practicable after the Effective Time, Holding Company shall
cause the Exchange Agent to send to each record holder of a certificate or
certificates which, at the Effective Time, represent outstanding shares of CRA
Common Stock or OSI Common Stock (the "Certificates"), which holder's shares of
CRA Common Stock or OSI Common Stock were converted into the right to receive
shares of Holding Company Common Stock (the "Converted Stock") pursuant to
Section 4.3 and 4.4, respectively, (i) a letter of transmittal (which shall
specify that delivery shall be effected, and risk of loss and title to the
certificates theretofore representing the Converted Stock shall pass, only upon
delivery of the Certificates to the Exchange Agent and shall be in such form and
contain such other provisions as Holding Company shall reasonably determine),
and (ii) instructions for use in effecting the surrender of the Certificates in
exchange for certificates representing shares of Holding Company Common Stock.
Upon surrender of a Certificate for cancellation to the Exchange Agent, together
with such letter of transmittal, duly executed, the holder of such Certificate
shall be entitled to receive in exchange therefor a certificate representing
that number of whole shares of Holding Company Common Stock and cash in lieu of
fractional shares as contemplated by Section 4.5, if any, which such holder has
the right to receive pursuant to the provisions of this Article 4, and the
Certificate so surrendered shall forthwith be canceled. In the event of a
transfer of ownership of Converted Stock which is not registered in the transfer
records of the Company, a certificate evidencing the proper number of shares of
Holding Company Common Stock may be issued to the transferee if the certificate
evidencing the Converted Stock, as the case may be, shall be surrendered to the
Exchange Agent, accompanied by all documents required to evidence and effect
such transfer and by
 
                                      A-6
<PAGE>
evidence that any applicable stock transfer taxes have been paid. Until
surrender for exchange in accordance with the provisions of Section 4.6 of this
Agreement, each Certificate theretofore representing shares of Converted Stock
(other than any CRA Dissenting Shares) shall from and after the Effective Time
represent for all purposes only the right to receive the number of shares of
Holding Company Common Stock and cash in lieu of fractional shares, if any, as
set forth in this Agreement. If any holder of Converted Stock shall be unable to
surrender such holder's Certificates because such Certificates have been lost or
destroyed, such holder may deliver in lieu thereof an affidavit and indemnity
bond in the form and substance and with surety reasonably satisfactory to
Holding Company.
 
    (c) No dividends or other distributions with respect to Holding Company
Common Stock declared or made after the Effective Time with a record date after
the Effective Time shall be paid to the holder of any unsurrendered Certificate
with respect to the right to receive shares of Holding Company Common Stock
represented thereby, and no cash payment in lieu of fractional shares shall be
paid to any such holder pursuant to Section 4.5, until the holder of such
Certificate shall surrender such Certificate in accordance herewith. Subject to
the effect of applicable laws, following the surrender of any such Certificate,
there shall be paid to the holder thereof, without interest: (i) at the time of
such surrender, the amount of any cash payable in lieu of a fractional share of
Holding Company Common Stock to which such holder is entitled pursuant to
Section 4.5 and the amount of dividends or distributions with a record date
after the Effective Time theretofore paid with respect to such whole shares of
Holding Company Common Stock, if any; and (ii) at the appropriate payment date,
the amount of dividends or other distributions with a record date after the
Effective Time but prior to such surrender and a payment date subsequent to such
surrender payable with respect to such whole shares of Holding Company Common
Stock, if any.
 
    (d) All shares of Holding Company Common Stock issued upon surrender for
exchange of shares of Converted Stock in accordance with the terms hereof
(including any cash paid pursuant to Section 4.5) shall be deemed to have been
issued in full satisfaction of all rights pertaining to such shares of Converted
Stock.
 
    (e) Any portion of the Exchange Fund that remains unclaimed by the former
holders of Converted Stock on the first anniversary of the Closing Date shall be
delivered to Holding Company upon demand, and any former holders of Converted
Stock who have not theretofore complied with this Article 4 shall thereafter
look only to Holding Company for the number of shares of Holding Company Common
Stock and cash in lieu of fractional shares, if any, as set forth in this
Agreement. Holding Company shall not be liable to any former holder of Converted
Stock for any Holding Company Common Stock or cash delivered to a public
official pursuant to any applicable abandoned property, escheat or similar law.
 
    (f) Holding Company (or any affiliate thereof) shall be entitled to deduct
and withhold from the consideration otherwise payable pursuant to this Agreement
to any former holder of Converted Stock such amounts as Holding Company (or any
affiliate thereof) is required to deduct and withhold with respect to the making
of such payment under the Code or any other provision of federal, state, local
or foreign tax law and Holding Company agrees to remit to the proper taxing
authority such amounts so withheld. To the extent that amounts are so withheld
by Holding Company, such withheld amounts shall be treated for all purposes of
this Agreement as having been paid to the former holder of Converted Stock in
respect of which such deduction and withholding was made by Holding Company.
Holding Company shall, within a reasonable period of time prior to withholding
any such amount, inform CRA and OSI of its intent to deduct and withhold any
amounts pursuant to this Section 4.6(d) and will cooperate with CRA and OSI in
taking commercially reasonable actions necessary to avoid and/or minimize the
amounts required to be deducted and withheld from the consideration payable
pursuant to this Agreement. Holding Company agrees to promptly pay to the former
holders of Converted Stock any refunded amounts received by Holding Company that
are attributable to such withholding.
 
    (g) Certificates surrendered for exchange by any person constituting an
"affiliate" of CRA or OSI for purposes of Rule 145(c) under the Securities Act
of 1933, as amended (the "Securities Act"), shall not be exchanged until Holding
Company has received a written agreement from such person as provided in Section
7.10.
 
                                      A-7
<PAGE>
                                   ARTICLE 5
 
                     REPRESENTATIONS AND WARRANTIES OF OSI
 
    Except as set forth in the disclosure letter delivered at or prior to the
execution hereof to CRA (the "OSI Disclosure Letter") or in OSI Reports (as
defined below), OSI represents and warrants to CRA as of the date of this
Agreement as follows:
 
    5.1.  EXISTENCE; GOOD STANDING; CORPORATE AUTHORITY.  OSI is a corporation
duly incorporated, validly existing and in good standing under the laws of its
jurisdiction of incorporation. OSI is duly licensed or qualified to do business
as a foreign corporation and is in good standing under the laws of any other
state of the United States in which the character of the properties owned or
leased by it or in which the transaction of its business makes such
qualification necessary, except where the failure to be so qualified or to be in
good standing would not have a material adverse effect on the business, results
of operations, financial condition or prospects of OSI and its Subsidiaries
taken as a whole (an "OSI Material Adverse Effect"). OSI has all requisite
corporate power and authority to own, operate and lease its properties and carry
on its business as now conducted. Each of OSI's Significant Subsidiaries (as
defined in Section 10.14 hereof) is a corporation, partnership or limited
liability company duly organized, validly existing and in good standing under
the laws of its jurisdiction of incorporation or organization, has the
corporate, partnership or other similar power and authority to own its
properties and to carry on its business as it is now being conducted, and is
duly qualified to do business and is in good standing in each jurisdiction in
which the ownership of its property or the conduct of its business requires such
qualification, except for jurisdictions in which such failure to be so qualified
or to be in good standing would not have an OSI Material Adverse Effect. The
copies of OSI's Certificate of Incorporation and Bylaws previously made
available to CRA are true and correct.
 
    5.2.  AUTHORIZATION, VALIDITY AND EFFECT OF AGREEMENTS.  OSI has the
requisite corporate power and authority to execute and deliver this Agreement
and all agreements and documents contemplated hereby. Subject only to the
approval of this Agreement and the transactions contemplated hereby by the
holders of a majority of the outstanding shares of OSI Common Stock, the
consummation by OSI of the transactions contemplated hereby has been duly
authorized by all requisite corporate action. This Agreement constitutes, and
all agreements and documents contemplated hereby (when executed and delivered
pursuant hereto for value received) will constitute, the valid and legally
binding obligations of OSI, enforceable in accordance with their respective
terms, subject to applicable bankruptcy, insolvency, moratorium or other similar
laws relating to creditors' rights and general principles of equity.
 
    5.3.  CAPITALIZATION.  The authorized capital stock of OSI consists of
50,000,000 shares of OSI Common Stock and 20,000,000 shares of preferred stock,
no par value (the "OSI Preferred Stock"). As of March 31, 1997, (a) 21,579,898
shares of OSI Common Stock were issued and outstanding, (b) no shares of
preferred stock were issued and outstanding, (c) 2,518,094 shares of OSI Common
Stock were reserved for issuance pursuant to the OSI Stock Option Plans, (d)
there were no shares of OSI Common Stock held in OSI's treasury, (e) 200,000
shares of OSI Common Stock were reserved for issuance pursuant to certain
warrants issued by OSI, (f) 3,291,246 shares of OSI Common Stock were reserved
for issuance upon conversion of the 6% Convertible Subordinated Notes due 2001
of OSI in the aggregate principal amount of $97,750,000 (the "OSI Convertible
Notes") and (g) 26,482 shares of OSI Common Stock were reserved for issuance
upon conversion of that certain 6% Convertible Promissory Note dated October 1,
1993 issued by OSI to John Anderson, D.O. in connection with the Stock Purchase
Agreement dated October 1, 1993 between an OSI Subsidiary and John Anderson,
D.O. (the "Anderson Note"). Since March 31, 1997, (i) no additional shares of
capital stock of OSI have been issued, except pursuant to the terms existing on
the date hereof of the OSI Stock Option Plans and (ii) no options or other
rights to acquire shares of OSI's capital stock have been granted (other than
(i) options that have been or may be granted after March 31, 1997 to individuals
other than executive officers of OSI to acquire up to 15,000 shares of OSI
Common
 
                                      A-8
<PAGE>
Stock pursuant to the terms of the OSI Stock Option Plans at an exercise price
of not less than the fair market value of the OSI Common Stock on the date of
grant and (ii) the option granted to CRA on the date hereof). Other than the OSI
Convertible Notes and the Anderson Note, OSI has no outstanding bonds,
debentures, notes or other obligations the holders of which have the right to
vote (or which are convertible into or exercisable for securities having the
right to vote) with the stockholders of OSI on any matter. All issued and
outstanding shares of OSI Common Stock are duly authorized, validly issued,
fully paid, nonassessable and free of preemptive rights. There are not at the
date of this Agreement any existing options, warrants, calls, subscriptions,
convertible securities, or other rights, agreements or commitments which
obligate OSI or any of its Subsidiaries to issue, transfer or sell any shares of
capital stock of OSI or any of its Subsidiaries (other than under the OSI Stock
Option Plans, the OSI Convertible Notes and the Anderson Note).
 
    5.4.  SUBSIDIARIES.  OSI owns directly or indirectly each of the outstanding
shares of capital stock (or other ownership interests having by their terms
ordinary voting power to elect a majority of directors or others performing
similar functions with respect to such OSI Significant Subsidiary) of each of
OSI's Significant Subsidiaries. Each of the outstanding shares of capital stock
of each of OSI's Significant Subsidiaries is duly authorized, validly issued,
fully paid and nonassessable, and is owned, directly or indirectly, by OSI. Each
of the outstanding shares of capital stock of each Significant Subsidiary of OSI
is owned, directly or indirectly, by OSI free and clear of all liens, pledges,
security interests, claims or other encumbrances other than liens in favor of
Creditanstalt-Bankverein, as agent, under OSI's existing Loan and Security
Agreement therewith and liens imposed by local law which are not material. The
following information for each Significant Subsidiary of OSI has been previously
provided to CRA, if applicable: (i) its name and jurisdiction of incorporation
or organization; (ii) its authorized capital stock or share capital; and (iii)
the number of issued and outstanding shares of capital stock or share capital.
All of the Subsidiaries of OSI other than the Significant Subsidiaries, when
taken together, do not in the aggregate constitute a Significant Subsidiary of
OSI.
 
    5.5.  OTHER INTERESTS.  Except for interests in OSI Subsidiaries, neither
OSI nor any OSI Significant Subsidiary owns directly or indirectly any interest
or investment (whether equity or debt) in any corporation, partnership, joint
venture, business, trust or entity (other than investments of less than
$1,000,000 in the aggregate).
 
    5.6.  NO CONFLICT; REQUIRED FILINGS AND CONSENTS.  (a) The execution and
delivery of this Agreement by OSI do not, and the consummation by OSI of the
transactions contemplated hereby will not, (i) conflict with or violate the
certificate of incorporation or by-laws or equivalent organizational documents
of (x) OSI or (y) any OSI Significant Subsidiary, (ii) subject to making the
filings and obtaining the approvals identified in Section 5.6(b) hereof,
conflict with or violate any law, rule, regulation, order, judgment or decree
applicable to OSI or any OSI Subsidiary or by which any property or asset of OSI
or any OSI Subsidiary is bound or affected, or (iii) subject to making the
filings and obtaining the approvals identified in Section 5.6(b) hereof, result
in any breach of or constitute a default (or an event which with notice or lapse
of time or both would become a default) under, result in the loss of a material
benefit under, or give to others any right of purchase or sale, or any right of
termination, amendment, acceleration, increased payments or cancellation of, or
result in the creation of a lien or other encumbrance on any property or asset
of OSI or any OSI Subsidiary pursuant to, any note, bond, mortgage, indenture,
contract, agreement, lease, license, permit, franchise or other instrument or
obligation to which OSI or any OSI Subsidiary is a party or by which OSI or any
OSI Subsidiary or any property or asset of OSI or any OSI Subsidiary is bound or
affected, except, in the case of clauses (i)(y), (ii) and (iii), for any such
conflicts, violations, breaches, defaults or other occurrences which would not
prevent or delay consummation of any of the transactions contemplated hereby in
any material respect, or otherwise prevent OSI from performing its obligations
under this Agreement in any material respect, and would not, individually or in
the aggregate, have an OSI Material Adverse Effect. The execution and delivery
of this Agreement by OSI do not, and the consummation by OSI of the transactions
contemplated hereby will not, result in any material breach
 
                                      A-9
<PAGE>
of or constitute a material default (or an event which with notice or lapse of
time or both would become a material default) under, result in the loss of a
material benefit under, or give to others any right of purchase or sale, or any
right of termination, amendment, acceleration, increased payments or
cancellation of, or result in the creation of a lien or other encumbrance on any
property or asset of OSI or any OSI Subsidiary pursuant to, any Material
Contract to which OSI or any OSI Subsidiary is a party or by which OSI or any
OSI Subsidiary or any property or asset of OSI or any OSI Subsidiary is bound or
affected. For the purposes hereof, "Material Contract", as such term relates to
OSI, shall mean any note, bond, mortgage, indenture, contract, agreement, lease,
license, permit, franchise or other instrument or obligation that is required to
be listed as an Exhibit to OSI's Form 10-K filed with the SEC (as hereinafter
defined) with respect to its year ended December 31, 1996.
 
    (b) The execution and delivery of this Agreement by OSI do not, and the
performance of this Agreement and the consummation by OSI of the transactions
contemplated hereby will not, require any consent, approval, authorization or
permit of, or filing with or notification to, any governmental or regulatory
authority, domestic or foreign (each a "Governmental Entity"), except (i) for
(A) applicable requirements, if any, of the Securities Exchange Act of 1934, as
amended (the "Exchange Act"), the Securities Act of 1933, as amended (the
"Securities Act"), state securities or "blue sky" laws ("Blue Sky Laws") and
state takeover laws, (B) the pre-merger notification requirements of the
Hart-Scott-Rodino Antitrust Improvements Act of 1976, as amended, and the rules
and regulations thereunder (the "HSR Act"), (C) filing and recordation of
appropriate merger and similar documents as required by Delaware law and
Massachusetts law and (D) applicable requirements, if any, of the Code and
state, local and foreign tax laws, and (ii) where failure to obtain such
consents, approvals, authorizations or permits, or to make such filings or
notifications, would not prevent or delay consummation of any of the
transactions contemplated hereby in any material respect, or otherwise prevent
OSI from performing its obligations under this Agreement in any material
respect, and would not, individually or in the aggregate, have an OSI Material
Adverse Effect.
 
    5.7.  COMPLIANCE.  Neither OSI nor any OSI Subsidiary is in conflict with,
or in default or violation of, (i) any law, rule, regulation, order, judgment or
decree applicable to OSI or any OSI Subsidiary or by which any property or asset
of OSI or any OSI Subsidiary is bound or affected, or (ii) any note, bond,
mortgage, indenture, contract, agreement, lease, license, permit, franchise or
other instrument or obligation to which OSI or any OSI Subsidiary is a party or
by which OSI or any OSI Subsidiary or any property or asset of OSI or any OSI
Subsidiary is bound or affected, in each case except for any such conflicts,
defaults or violations that would not, individually or in the aggregate, have an
OSI Material Adverse Effect. OSI and its Subsidiaries have obtained all
licenses, permits and other authorizations and have taken all actions required
by applicable law or governmental regulations in connection with their business
as now conducted, where the failure to obtain any such item or to take any such
action would have, individually or in the aggregate, an OSI Material Adverse
Effect.
 
    5.8.  SEC DOCUMENTS.  (a) OSI has filed all forms, reports and documents
required to be filed by it with the Securities and Exchange Commission ("SEC")
since May 8, 1995 (collectively, the "OSI Reports"). As of their respective
dates, the OSI Reports and any such reports, forms and other documents filed by
OSI with the SEC after the date of this Agreement (i) complied, or will comply,
as to form in all material respects with the applicable requirements of the
Securities Act, the Exchange Act, and the rules and regulations thereunder and
(ii) did not, or will not, contain any untrue statement of a material fact or
omit to state a material fact required to be stated therein or necessary to make
the statements made therein, in the light of the circumstances under which they
were made, not misleading. The representation in clause (ii) of the preceding
sentence shall not apply to any misstatement or omission in any OSI Report filed
prior to the date of this Agreement which was superseded by a subsequent OSI
Report filed prior to the date of this Agreement. No OSI Subsidiary is required
to file any report, form or other document with the SEC.
 
                                      A-10
<PAGE>
    (b) Each of the consolidated balance sheets of OSI included in or
incorporated by reference into OSI Reports (including the related notes and
schedules) fairly presents the consolidated financial position of OSI and OSI
Subsidiaries as of its date, and each of the consolidated statements of income,
retained earnings and cash flows of OSI included in or incorporated by reference
into OSI Reports (including any related notes and schedules) fairly presents the
results of operations, retained earnings or cash flows, as the case may be, of
OSI and the OSI Subsidiaries for the periods set forth therein (subject, in the
case of unaudited statements, to normal year-end audit adjustments which would
not be material in amount or effect), in each case in accordance with generally
accepted accounting principles consistently applied during the periods involved,
except as may be noted therein. Neither OSI nor any of the OSI Subsidiaries has
any liabilities or obligations of any nature (whether accrued, absolute,
contingent or otherwise) that would be required to be reflected on, or reserved
against in, a balance sheet of OSI or in the notes thereto, prepared in
accordance with generally accepted accounting principles consistently applied,
except for (i) liabilities or obligations that were so reserved on, or reflected
in (including the notes to), the consolidated balance sheet of OSI as of
December 31, 1996; (ii) liabilities or obligations arising in the ordinary
course of business since December 31, 1996 and (iii) liabilities or obligations
which would not, individually or in the aggregate, have an OSI Material Adverse
Effect.
 
    5.9.  LITIGATION.  There are no actions, suits or proceedings pending
against OSI or the OSI Subsidiaries or, to the actual knowledge of the executive
officers of OSI, threatened against OSI or the OSI Subsidiaries, at law or in
equity, or before or by any federal or state commission, board, bureau, agency
or instrumentality, that are reasonably likely to have an OSI Material Adverse
Effect.
 
    5.10.  ABSENCE OF CERTAIN CHANGES.  Except as specifically contemplated by
this Agreement, since December 31, 1996, there has not been (i) any OSI Material
Adverse Effect; (ii) any declaration, setting aside or payment of any dividend
or other distribution with respect to its capital stock; or (iii) any material
change in its accounting principles, practices or methods.
 
    5.11.  TAXES.  (a) OSI and each of the OSI Subsidiaries has filed all
material tax returns and reports required to be filed by it, or requests for
extensions to file such returns or reports have been timely filed and granted
and have not expired, and all tax returns and reports are complete and accurate
in all respects, except to the extent that such failures to file, have
extensions granted that remain in effect or be complete and accurate in all
respects, as applicable, individually or in the aggregate, would not have an OSI
Material Adverse Effect. OSI and each of the OSI Subsidiaries have paid (or OSI
has paid on its behalf) all taxes shown as due on such tax returns and reports.
The most recent financial statements contained in the OSI Reports reflect an
adequate reserve for all taxes payable by OSI and the OSI Subsidiaries for all
taxable periods and portions thereof accrued through the date of such financial
statements, and no deficiencies for any taxes have been proposed, asserted or
assessed against OSI or any OSI Subsidiary that are not adequately reserved for,
except for inadequately reserved taxes and inadequately reserved deficiencies
that would not, individually or in the aggregate, have an OSI Material Adverse
Effect. No requests for waivers of the time to assess any taxes against OSI or
any OSI Subsidiary have been granted or are pending, except for requests with
respect to such taxes that have been adequately reserved for in the most recent
financial statements contained in the OSI Reports, or, to the extent not
adequately reserved, the assessment of which would not, individually or in the
aggregate, have an OSI Material Adverse Effect.
 
    (b) Neither OSI nor any OSI Subsidiary has taken any action or has any
knowledge of any fact or circumstance that is reasonably likely to prevent the
OSI Merger from qualifying as a reorganization governed by Section 368(a) of the
Code.
 
    (c) As used herein, "taxes" shall include all Federal, state, local and
foreign income, franchise, property, sales, use, excise and other taxes, fees,
assessments or charges of any kind or nature whatsoever imposed by any
governmental authority, including obligations for withholding taxes from
payments due or made to any other person and any interest, penalties or
additions to tax.
 
                                      A-11
<PAGE>
    5.12  EMPLOYEE BENEFIT PLANS.
 
        (a) The OSI Disclosure Letter lists each of the following which is
    sponsored, maintained, or contributed to by OSI or any OSI Subsidiary for
    the benefit of any current or former employees, officers, or directors of
    OSI or any OSI Subsidiary or for which OSI or any OSI Subsidiary has any
    liability or contingent liability;
 
        (i) each "employee benefit plan," as such term is defined in Section
    3(3) of the Employee Retirement Income Security Act of 1974, as amended
    ("ERISA") (each an "OSI ERISA Plan");
 
        (ii) each employment, severance, termination, retention,
    stay-with-bonus, or change-of-control agreement or understanding (each an
    "OSI Employment Agreement"), except that the OSI Disclosure Letter only
    lists OSI Employment Agreements with OSI's executive officers; and
 
       (iii) each personnel policy, stock option or purchase plan, collective
    bargaining agreement, bonus plan or arrangement, incentive award plan or
    arrangement, vacation policy, deferred compensation agreement or
    arrangement, executive compensation or supplemental income arrangement, and
    each other employee benefit plan, agreement, arrangement, program, practice
    or understanding (each, an "OSI Benefit Program"), except that the OSI
    Disclosure Letter only lists OSI Benefit Programs that are for the exclusive
    benefit of one or more of OSI's executive officers. The OSI ERISA Plans, the
    OSI Employment Agreements and the OSI Benefit Programs are sometimes
    collectively hereinafter referred to as the "OSI Plans".
 
        (b) True, correct and complete copies of each of the OSI ERISA Plans,
    and related trusts, if applicable, including all amendments thereto, have
    been furnished to CRA. There has also been furnished to CRA, with respect to
    each OSI ERISA Plan required to file such report and description, the most
    recent report on Form 5500 and the summary plan description. True, correct
    and complete copies or descriptions of all OSI Benefit Programs and
    Employment Agreements that are for the exclusive benefit of, or are with,
    OSI's executive officers have also been furnished to CRA. Each of the OSI
    ERISA Plans intended to be qualified under Section 401(a) of the Code
    satisfies the requirements of such section, and has received a favorable
    determination letter from the Internal Revenue Service regarding such
    qualified status (a copy of which has been provided to CRA) and has not,
    since receipt of the most favorable determination letter, been amended or,
    to the knowledge of OSI, operated in a way which would adversely affect such
    qualified status.
 
        (c) Each of the OSI Plans is in compliance in all material respects with
    all applicable requirements of law, including ERISA and the Code, and all
    reports and disclosures relating to the OSI Plans required to be filed with
    or furnished to governmental agencies, OSI Plan participants or OSI Plan
    beneficiaries have been filed or furnished in accordance with applicable law
    (except where the failure to file or furnish would not have an OSI Material
    Adverse Effect), and there are no actions, suits or claims pending (other
    than routine claims for benefits) or, to the knowledge of OSI, threatened
    against, or with respect to, any of the OSI Plans or their assets.
 
        (d) All contributions required to be made to the OSI Plans pursuant to
    their terms or provisions have been timely made (except where the failure to
    make such contributions would not have an OSI Material Adverse Effect).
 
        (e) None of the OSI Plans is a "defined benefit pension plan" within the
    meaning of section 3(35) of ERISA or is a "multiemployer plan" (within the
    meaning of section 3(37) of ERISA) without regard to whether any such plans
    are subject to Title IV of ERISA.
 
        (f) None of OSI or any OSI Subsidiary has made any payments, is
    obligated to make any payments, or is a party to any agreement that could
    obligate it to make any payments, that would not be deductible by reason of
    section 280G of the Code or that would be subject to an excise tax under
 
                                      A-12
<PAGE>
    section 4999 of the Code or, except as previously disclosed in writing to
    CRA, that would not be deductible by reason of section 162 of the Code.
 
        (g) Except as disclosed in the OSI Disclosure Letter, the execution of,
    and performance of the transactions contemplated in this Agreement will not
    (either alone or upon the occurrence of any additional or subsequent events)
    constitute an event under any OSI Plan or any trust or loan that will or may
    result in any payment (whether of severance pay or otherwise), acceleration,
    forgiveness of indebtedness, vesting, distribution, increase in benefits or
    obligations to fund benefits with respect to any current or former employee,
    officer, or director.
 
        (h) Other than coverage mandated by applicable statute, none of OSI or
    any OSI Subsidiary is under any obligation or liability to provide medical
    benefits or death benefits (including through insurance) to retirees or to
    former employees, officers, or directors of OSI or any OSI Subsidiary.
 
    5.13.  LABOR MATTERS.  There is no labor strike, labor dispute, work
slowdown, stoppage or lockout actually pending, or to the knowledge of the
executive officers of OSI, threatened against or affecting OSI or any OSI
Subsidiary, except as would not, individually or in the aggregate, have an OSI
Material Adverse Effect. There is no unfair labor practice or labor arbitration
proceeding pending or, to the knowledge of the executive officers of OSI,
threatened against OSI or its Subsidiaries relating to their business, except
for any such proceeding which would not have an OSI Material Adverse Effect.
 
    5.14.  NO BROKERS.  OSI has not entered into any contract, arrangement or
understanding with any person or firm which may result in the obligation of OSI,
Holding Company or CRA to pay any finder's fees, brokerage or agent's
commissions or other like payments in connection with the negotiations leading
to this Agreement or the consummation of the transactions contemplated hereby,
except that OSI has retained Donaldson, Lufkin & Jenrette Securities Corporation
("DLJ") as its financial advisor, the arrangements with which have been
disclosed in writing to CRA prior to the date hereof. Other than the foregoing
arrangements, OSI is not aware of any claim for payment of any finder's fees,
brokerage or agent's commissions or other like payments in connection with the
negotiations leading to this Agreement or the consummation of the transactions
contemplated hereby.
 
    5.15.  OPINION OF FINANCIAL ADVISOR.  OSI has received the opinion of DLJ to
the effect that, as of the date hereof, the Exchange Ratio is fair to the
holders of OSI Common Stock from a financial point of view. As used herein, the
"Exchange Ratio" means the quotient of the OSI Ratio divided by the CRA Ratio.
 
    5.16  PRELIMINARY POOLING LETTER.  OSI has received an opinion, dated as of
the date of this Agreement, from its independent accountants, Arthur Andersen,
L.L.P., to the effect that if the business combination to be effected by the
Mergers were to occur on the date hereof they would be properly accounted for as
a pooling-of-interests. OSI is aware of no reasons why the transactions
contemplated hereby would not be properly accounted for as a
pooling-of-interests.
 
                                   ARTICLE 6
 
                     REPRESENTATIONS AND WARRANTIES OF CRA
 
    Except as set forth in the disclosure letter delivered at or prior to the
execution hereof to OSI (the "CRA Disclosure Letter") or in CRA Reports (as
defined below), CRA represents and warrants to OSI as of the date of this
Agreement as follows:
 
    6.1.  EXISTENCE; GOOD STANDING; CORPORATE AUTHORITY.  CRA is a corporation
duly incorporated, validly existing and in good standing under the laws of its
jurisdiction of incorporation. CRA is duly licensed or qualified to do business
as a foreign corporation and is in good standing under the laws of any other
state of the United States in which the character of the properties owned or
leased by it or in which the transaction of its business makes such
qualification necessary, except where the failure to be so qualified or
 
                                      A-13
<PAGE>
to be in good standing would not have a material adverse effect on the business,
results of operations, financial condition or prospects of CRA and its
Subsidiaries taken as a whole (a "CRA Material Adverse Effect"). CRA has all
requisite corporate power and authority to own, operate and lease its properties
and carry on its business as now conducted. Each of CRA's Significant
Subsidiaries (as defined in Section 10.14 hereof) is a corporation or
partnership duly organized, validly existing and in good standing under the laws
of its jurisdiction of incorporation or organization, has the corporate or
partnership power and authority to own its properties and to carry on its
business as it is now being conducted, and is duly qualified to do business and
is in good standing in each jurisdiction in which the ownership of its property
or the conduct of its business requires such qualification, except for
jurisdictions in which such failure to be so qualified or to be in good standing
would not have a CRA Material Adverse Effect. The copies of CRA's Articles of
Organization and Bylaws previously made available to OSI are true and correct.
 
    6.2.  AUTHORIZATION, VALIDITY AND EFFECT OF AGREEMENTS.  CRA has the
requisite corporate power and authority to execute and deliver this Agreement
and all agreements and documents contemplated hereby. Subject only to the
approval of this Agreement and the transactions contemplated hereby by the
holders of two-thirds of the outstanding shares of CRA Common Stock, the
consummation by CRA of the transactions contemplated hereby has been duly
authorized by all requisite corporate action. This Agreement constitutes, and
all agreements and documents contemplated hereby (when executed and delivered
pursuant hereto for value received) will constitute, the valid and legally
binding obligations of CRA, enforceable in accordance with their respective
terms, subject to applicable bankruptcy, insolvency, moratorium or other similar
laws relating to creditors' rights and general principles of equity.
 
    6.3.  CAPITALIZATION.  The authorized capital stock of CRA consists of
40,000,000 shares of CRA Common Stock and 1,000,000 shares of preferred stock,
$.01 par value (the "CRA Preferred Stock"). As of March 31, 1997, (a) 8,961,985
shares of CRA Common Stock were issued and outstanding, (b) no shares of
preferred stock were issued and outstanding, (c) 1,070,000 shares of CRA Common
Stock were reserved for issuance pursuant to CRA Stock Option Plans and (d)
there were no shares of CRA Common Stock held in CRA's treasury. Since such
date, (i) no additional shares of capital stock of CRA have been issued, except
pursuant to the terms existing on the date hereof of the CRA Stock Option Plans
and (ii) no options or other rights to acquire shares of CRA's capital stock
have been granted (other than (i) options that have been or may be granted after
March 31, 1997 to individuals other than to executive officers of CRA to acquire
up to 15,000 shares of CRA Common Stock pursuant to the terms of the CRA Stock
Option Plans at an exercise price of not less than the fair market value of the
CRA Common Stock on the date of grant and (ii) the option granted to OSI on the
date hereof). CRA has no outstanding bonds, debentures, notes or other
obligations the holders of which have the right to vote (or which are
convertible into or exercisable for securities having the right to vote) with
the stockholders of CRA on any matter. All issued and outstanding shares of CRA
Common Stock are duly authorized, validly issued, fully paid, nonassessable and
free of preemptive rights. There are not at the date of this Agreement any
existing options, warrants, calls, subscriptions, convertible securities, or
other rights, agreements or commitments which obligate CRA or any of its
Subsidiaries to issue, transfer or sell any shares of capital stock of CRA or
any of its Subsidiaries (other than under the CRA Stock Option Plans).
 
    6.4.  SUBSIDIARIES.  CRA owns directly or indirectly each of the outstanding
shares of capital stock (or other ownership interests having by their terms
ordinary voting power to elect a majority of directors or others performing
similar functions with respect to such CRA Significant Subsidiary) of each of
CRA's Significant Subsidiaries. Each of the Outstanding shares of capital stock
of each of CRA's Significant Subsidiaries is duly authorized, validly issued,
fully paid and nonassessable, and is owned, directly or indirectly, by CRA. Each
of the outstanding shares of capital stock of each Significant Subsidiary of CRA
is owned, directly or indirectly, by CRA free and clear of all liens, pledges,
security interests, claims or other encumbrances other than liens imposed by
local law which are not material. The following information for each Significant
Subsidiary of CRA has been previously provided to OSI, if applicable: (i) its
name and jurisdiction of incorporation or organization; (ii) its authorized
capital stock or share capital; and (iii) the
 
                                      A-14
<PAGE>
number of issued and outstanding shares of capital stock or share capital. All
of the Subsidiaries of CRA other than the Significant Subsidiaries, when taken
together, do not in the aggregate constitute a Significant Subsidiary of CRA.
 
    6.5.  OTHER INTERESTS.  Except for interests in CRA Subsidiaries, neither
CRA nor any CRA Significant Subsidiary owns directly or indirectly any interest
or investment (whether equity or debt) in any corporation, partnership, joint
venture, business, trust or entity (other than investments of less than
$1,000,000 in the aggregate).
 
    6.6.  NO CONFLICT; REQUIRED FILINGS AND CONSENTS.  (a) The execution and
delivery of this Agreement by CRA do not, and the consummation by CRA of the
transactions contemplated hereby will not, (i) conflict with or violate the
certificate of incorporation or by-laws or equivalent organizational documents
of (x) CRA or (y) any CRA Significant Subsidiary, (ii) subject to making the
filings and obtaining the approvals identified in Section 6.6(b) hereof,
conflict with or violate any law, rule, regulation, order, judgment or decree
applicable to CRA or any CRA Subsidiary or by which any property or asset of CRA
or any CRA Subsidiary is bound or affected, or (iii) subject to making the
filings and obtaining the approvals identified in Section 6.6(b) hereof, result
in any breach of or constitute a default (or an event which with notice or lapse
of time or both would become a default) under, result in the loss of a material
benefit under, or give to others any right of purchase or sale, or any right of
termination, amendment, acceleration, increased payments or cancellation of, or
result in the creation of a lien or other encumbrance on any property or asset
of CRA or any CRA Subsidiary pursuant to, any note, bond, mortgage, indenture,
contract, agreement, lease, license, permit, franchise or other instrument or
obligation to which CRA or any CRA Subsidiary is a party or by which CRA or any
CRA Subsidiary or any property or asset of CRA or any CRA Subsidiary is bound or
affected, except, in the case of clauses (i)(y), (ii) and (iii), for any such
conflicts, violations, breaches, defaults or other occurrences which would not
prevent or delay consummation of any of the transactions contemplated hereby in
any material respect, or otherwise prevent CRA from performing its obligations
under this Agreement in any material respect, and would not, individually or in
the aggregate, have a CRA Material Adverse Effect. The execution and delivery of
this Agreement by CRA do not, and the consummation by CRA of the transactions
contemplated hereby will not, result in any material breach of or constitute a
material default (or an event which with notice or lapse of time or both would
become a material default) under, result in the loss of a material benefit
under, or give to others any right of purchase or sale, or any right of
termination, amendment, acceleration, increased payments or cancellation of, or
result in the creation of a lien or other encumbrance on any property or asset
of CRA or any CRA Subsidiary pursuant to, any Material Contract to which CRA or
any CRA Subsidiary is a party or by which CRA or any CRA Subsidiary or any
property or asset of CRA or any CRA Subsidiary is bound or affected. For the
purposes hereof, "Material Contract", as such term relates to CRA, shall mean
any note, bond, mortgage, indenture, contract, agreement, lease, license,
permit, franchise or other instrument or obligation that is required to be
listed as an Exhibit to CRA's Form 10-K filed with the SEC with respect to its
year ended December 31, 1996.
 
    (b) The execution and delivery of this Agreement by CRA do not, and the
performance of this Agreement and the consummation by CRA of the transactions
contemplated hereby will not, require any consent, approval, authorization or
permit of, or filing with or notification to, any governmental or regulatory
authority, domestic or foreign (each a "Governmental Entity"), except (i) for
(A) applicable requirements, if any, of the Securities Exchange Act of 1934, as
amended (the "Exchange Act"), the Securities Act of 1933, as amended (the
"Securities Act"), state securities or "blue sky" laws ("Blue Sky Laws") and
state takeover laws, (B) the pre-merger notification requirements of the
Hart-Scott-Rodino Antitrust Improvements Act of 1976, as amended, and the rules
and regulations thereunder (the "HSR Act"), (C) filing and recordation of
appropriate merger and similar documents as required by Delaware law and
Massachusetts law and (D) applicable requirements, if any, of the Code and
state, local and foreign tax laws, and (ii) where failure to obtain such
consents, approvals, authorizations or permits, or to make such filings or
notifications, would not prevent or delay consummation of any of the
transactions contemplated hereby in any material respect, or otherwise prevent
CRA from performing its obligations
 
                                      A-15
<PAGE>
under this Agreement in any material respect, and would not, individually or in
the aggregate, have a CRA Material Adverse Effect.
 
    6.7.  COMPLIANCE.  Neither CRA nor any CRA Subsidiary is in conflict with,
or in default or violation of, (i) any law, rule, regulation, order, judgment or
decree applicable to CRA or any CRA Subsidiary or by which any property or asset
of CRA or any CRA Subsidiary is bound or affected, or (ii) any note, bond,
mortgage, indenture, contract, agreement, lease, license, permit, franchise or
other instrument or obligation to which CRA or any CRA Subsidiary is a party or
by which CRA or any CRA Subsidiary or any property or asset of CRA or any CRA
Subsidiary is bound or affected, in each case except for any such conflicts,
defaults or violations that would not, individually or in the aggregate, have a
CRA Material Adverse Effect. CRA and its Subsidiaries have obtained all
licenses, permits and other authorizations and have taken all actions required
by applicable law or governmental regulations in connection with their business
as now conducted, where the failure to obtain any such item or to take any such
action would have, individually or in the aggregate, a CRA Material Adverse
Effect.
 
    6.8.  SEC DOCUMENTS.  (a) CRA has filed all forms, reports and documents
required to be filed by it with the Securities and Exchange Commission ("SEC")
since May 3, 1995 (collectively, the "CRA Reports"). As of their respective
dates, the CRA Reports and any such reports, forms and other documents filed by
CRA with the SEC after the date of this Agreement (i) complied, or will comply,
as to form in all material respects with the applicable requirements of the
Securities Act, the Exchange Act, and the rules and regulations thereunder and
(ii) did not, or will not, contain any untrue statement of a material fact or
omit to state a material fact required to be stated therein or necessary to make
the statements made therein, in the light of the circumstances under which they
were made, not misleading. The representation in clause (ii) of the preceding
sentence shall not apply to any misstatement or omission in any CRA Report filed
prior to the date of this Agreement which was superseded by a subsequent CRA
Report filed prior to the date of this Agreement. No CRA Subsidiary is required
to file any report, form or other document with the SEC.
 
    (b) Each of the consolidated balance sheets of CRA included in or
incorporated by reference into the CRA Reports (including the related notes and
schedules) fairly presents the consolidated financial position of CRA and the
CRA Subsidiaries as of its date, and each of the consolidated statements of
income, retained earnings and cash flows of CRA included in or incorporated by
reference into the CRA Reports (including any related notes and schedules)
fairly presents the results of operations, retained earnings or cash flows, as
the case may be, of CRA and the CRA Subsidiaries for the periods set forth
therein (subject, in the case of unaudited statements, to normal year-end audit
adjustments which would not be material in amount or effect), in each case in
accordance with generally accepted accounting principles consistently applied
during the periods involved, except as may be noted therein. Neither CRA nor any
of the CRA Subsidiaries has any liabilities or obligations of any nature
(whether accrued, absolute, contingent or otherwise) that would be required to
be reflected on, or reserved against in, a balance sheet of CRA or in the notes
thereto, prepared in accordance with generally accepted accounting principles
consistently applied, except for (i) liabilities or obligations that were so
reserved on, or reflected in (including the notes to), the consolidated balance
sheet of CRA as of December 31, 1996; (ii) liabilities or obligations arising in
the ordinary course of business since December 31, 1996 and (iii) liabilities or
obligations which would not, individually or in the aggregate, have a CRA
Material Adverse Effect.
 
    6.9.  LITIGATION.  There are no actions, suits or proceedings pending
against CRA or the CRA Subsidiaries or, to the actual knowledge of the executive
officers of CRA, threatened against CRA or the CRA Subsidiaries, at law or in
equity, or before or by any federal or state commission, board, bureau, agency
or instrumentality, that are reasonably likely to have a CRA Material Adverse
Effect.
 
    6.10.  ABSENCE OF CERTAIN CHANGES.  Except as specifically contemplated by
this Agreement, since December 31, 1996, there has not been (i) any CRA Material
Adverse Effect; (ii) any declaration, setting aside or payment of any dividend
or other distribution with respect to its capital stock; or (iii) any material
change in its accounting principles, practices or methods.
 
                                      A-16
<PAGE>
    6.11.  TAXES.  (a) CRA and each of the CRA Subsidiaries has filed all
material tax returns and reports required to be filed by it, or requests for
extensions to file such returns or reports have been timely filed and granted
and have not expired, and all tax returns and reports are complete and accurate
in all respects, except to the extent that such failures to file, have
extensions granted that remain in effect or be complete and accurate in all
respects, as applicable, individually or in the aggregate, would not have a CRA
Material Adverse Effect. CRA and each of the CRA Subsidiaries have paid (or CRA
has paid on its behalf) all taxes shown as due on such tax returns and reports.
The most recent financial statements contained in the CRA Reports reflect an
adequate reserve for all taxes payable by CRA and the CRA Subsidiaries for all
taxable periods and portions thereof accrued through the date of such financial
statements, and no deficiencies for any taxes have been proposed, asserted or
assessed against CRA or any CRA Subsidiary that are not adequately reserved for,
except for inadequately reserved taxes and inadequately reserved deficiencies
that would not, individually or in the aggregate, have a CRA Material Adverse
Effect. No requests for waivers of the time to assess any taxes against CRA or
any CRA Subsidiary have been granted or are pending, except for requests with
respect to such taxes that have been adequately reserved for in the most recent
financial statements contained in the CRA Reports, or, to the extent not
adequately reserved, the assessment of which would not, individually or in the
aggregate, have a CRA Material Adverse Effect.
 
    (b) Neither CRA nor any CRA Subsidiary has taken any action or has any
knowledge of any fact or circumstance that is reasonably likely to prevent the
CRA Merger from qualifying as a reorganization or an exchange governed by
Section 368(a) or Section 351(a) of the Code.
 
    (c) As used herein, "taxes" shall include all Federal, state, local and
foreign income, franchise, property, sales, use, excise and other taxes, fees,
assessments or charges of any kind or nature whatsoever imposed by any
governmental authority, including obligations for withholding taxes from
payments due or made to any other person and any interest, penalties or
additions to tax.
 
    6.12  EMPLOYEE BENEFIT PLANS.
 
        (a) The CRA Disclosure Letter lists each of the following which is
    sponsored, maintained, or contributed to by CRA or any CRA Subsidiary for
    the benefit of any current or former employees, officers, or directors of
    CRA or any CRA Subsidiary or for which CRA or any CRA Subsidiary has any
    liability or contingent liability:
 
        (i) each "employee benefit plan," as such term is defined in Section
    3(3) of the Employee Retirement Income Security Act of 1974, as amended
    ("ERISA") (each a "CRA ERISA Plan");
 
        (ii) each employment, severance, termination, retention,
    stay-with-bonus, or change-of-control agreement or understanding (each a
    "CRA Employment Agreement"), except that the CRA Disclosure Letter only
    lists CRA Employment Agreements with CRA's executive officers; and
 
       (iii) each personnel policy, stock option or purchase plan, collective
    bargaining agreement, bonus plan or arrangement, incentive award plan or
    arrangement, vacation policy, deferred compensation agreement or
    arrangement, executive compensation or supplemental income arrangement, and
    each other employee benefit plan, agreement, arrangement, program, practice
    or understanding (each, a "CRA Benefit Program"), except that the CRA
    Disclosure Letter only lists CRA Benefit Programs that are for the exclusive
    benefit of one or more of CRA's executive officers. The CRA ERISA Plans, the
    CRA Employment Agreements and the CRA Benefit Programs are sometimes
    collectively hereinafter referred to as the "CRA Plans".
 
        (b) True, correct and complete copies of each of the CRA ERISA Plans,
    and related trusts, if applicable, including all amendments thereto, have
    been furnished to OSI. There has also been furnished to OSI, with respect to
    each CRA ERISA Plan required to file such report and description, the most
    recent report on Form 5500 and the summary plan description. True, correct
    and complete copies or descriptions of all CRA Benefit Programs and
    Employment Agreements that are for the exclusive benefit of, or are with,
    CRA's executive officers have also been furnished to OSI. Each of the
 
                                      A-17
<PAGE>
    CRA ERISA Plans intended to be qualified under Section 401(a) of the Code
    satisfies the requirements of such section, and has received a favorable
    determination letter from the Internal Revenue Service regarding such
    qualified status (a copy of which has been provided to OSI) and has not,
    since receipt of the most favorable determination letter, been amended or,
    to the knowledge of CRA, operated in a way which would adversely affect such
    qualified status.
 
        (c) Each of the CRA Plans is in compliance in all material respects with
    all applicable requirements of law, including ERISA and the Code, and all
    reports and disclosures relating to the CRA Plans required to be filed with
    or furnished to governmental agencies, CRA Plan participants or CRA Plan
    beneficiaries have been filed or furnished in accordance with applicable law
    (except where the failure to file or furnish would not have a CRA Material
    Adverse Effect), and there are no actions, suits or claims pending (other
    than routine claims for benefits) or, to the knowledge of CRA, threatened
    against, or with respect to, any of the CRA Plans or their assets.
 
        (d) All contributions required to be made to the CRA Plans pursuant to
    their terms or provisions have been timely made (except where the failure to
    make such contributions would not have a CRA Material Adverse Effect).
 
        (e) None of the CRA Plans is a "defined benefit pension plan" within the
    meaning of section 3(35) of ERISA or is a "multiemployer plan" (within the
    meaning of section 3(37) of ERISA) without regard to whether any such plans
    are subject to Title IV of ERISA.
 
        (f) None of CRA or any CRA Subsidiary has made any payments, is
    obligated to make any payments, or is a party to any agreement that could
    obligate it to make any payments, that would not be deductible by reason of
    section 280G of the Code or that would be subject to an excise tax under
    section 4999 of the Code or, except as previously disclosed in writing to
    OSI, that would not be deductible by reason of section 162 of the Code.
 
        (g) Except as disclosed in the CRA Disclosure Letter, the execution of,
    and performance of the transactions contemplated in this Agreement will not
    (either alone or upon the occurrence of any additional or subsequent events)
    constitute an event under any CRA Plan or any trust or loan that will or may
    result in any payment (whether of severance pay or otherwise), acceleration,
    forgiveness of indebtedness, vesting, distribution, increase in benefits or
    obligations to fund benefits with respect to any current or former employee,
    officer, or director.
 
        (h) Other than coverage mandated by applicable statute, none of CRA or
    any CRA Subsidiary is under any obligation or liability to provide medical
    benefits or death benefits (including through insurance) to retirees or to
    former employees, officers, or directors of CRA or any CRA Subsidiary.
 
    6.13.  LABOR MATTERS.  There is no labor strike, labor dispute, work
slowdown, stoppage or lockout actually pending, or to the knowledge of the
executive officers of CRA, threatened against or affecting CRA or any CRA
Subsidiary, except as would not, individually or in the aggregate, have a CRA
Material Adverse Effect. There is no unfair labor practice or labor arbitration
proceeding pending or, to the knowledge of the executive officers of CRA,
threatened against CRA or its Subsidiaries relating to their business, except
for any such proceeding which would not have a CRA Material Adverse Effect.
 
    6.14.  NO BROKERS.  CRA has not entered into any contract, arrangement or
understanding with any person or firm which may result in the obligation of CRA,
Holding Company or OSI to pay any finder's fees, brokerage or agent's
commissions or other like payments in connection with the negotiations leading
to this Agreement or the consummation of the transactions contemplated hereby,
except that CRA has retained Alex. Brown & Sons Incorporated as its financial
advisor, the arrangements with which have been disclosed in writing to OSI prior
to the date hereof. Other than the foregoing arrangements, CRA is not aware of
any claim for payment of any finder's fees, brokerage or agent's commissions or
other like payments in connection with the negotiations leading to this
Agreement or the consummation of the transactions contemplated hereby.
 
                                      A-18
<PAGE>
    6.15.  OPINION OF FINANCIAL ADVISOR.  CRA has received the opinion of Alex.
Brown & Sons Incorporated to the effect that, as of the date hereof, the CRA
Ratio to be applied to the exchange of CRA Common Stock in the CRA Merger and
the OSI Ratio to be applied to the exchange of OSI Common Stock in the OSI
Merger are fair to the holders of CRA Common Stock from a financial point of
view.
 
    6.16  PRELIMINARY POOLING LETTER.  CRA has received an opinion, dated as of
the date of this Agreement, from its independent accountants, Arthur Andersen,
L.L.P., to the effect that if the business combination to be effected by the
Mergers were to occur on the date hereof they would be properly accounted for as
a pooling-of-interests. CRA is aware of no reasons why the transactions
contemplated hereby would not be properly accounted for as a
pooling-of-interests.
 
                                   ARTICLE 7
 
                                   COVENANTS
 
    7.1.  ALTERNATIVE PROPOSALS.
 
        (a) OSI Alternative Proposals.
 
        (i) From and after the date hereof, OSI will not, and will not authorize
    or (to the extent within its control) permit any of its officers, directors,
    employees, agents, Affiliates and other representatives or those of any of
    its Subsidiaries (collectively, "OSI Representatives") to, directly or
    indirectly, solicit or encourage (including by way of providing information)
    any prospective acquiror or the invitation or submission of any inquiries,
    proposals or offers or any other efforts or attempts that constitute, or may
    reasonably be expected to lead, to any OSI Acquisition Proposal (as
    hereinafter defined) from any person or engage in any discussions or
    negotiations with respect thereto or otherwise cooperate with or assist or
    participate in, or facilitate any such proposal; provided, however, that,
    notwithstanding any other provision of this Agreement (i) OSI's Board of
    Directors may take and disclose to the stockholders of OSI a position
    contemplated by Rule 14e-2(a) promulgated under the Exchange Act and (ii)
    following receipt from a third party, without any solicitation, initiation
    or encouragement, directly or indirectly, by OSI or any OSI Representative,
    of a bona fide OSI Acquisition Proposal, (x) OSI may engage in discussions
    or negotiations with such third party and may furnish such third party
    information concerning it, and its business, properties and assets if such
    third party executes a confidentiality agreement in reasonably customary
    form and (y) the Board of Directors of OSI may withdraw, modify or not make
    its recommendation referred to in Section 7.3 or terminate this Agreement in
    accordance with Article 9, but in each case referred to in the foregoing
    clauses (i) and (ii), only to the extent that OSI's Board of Directors shall
    conclude in good faith based on the advice of OSI's outside counsel that
    such action is necessary in order for OSI's Board of Directors to act in a
    manner that is consistent with its fiduciary obligations under applicable
    law.
 
        (ii) OSI shall immediately cease and cause to be terminated any existing
    solicitation, initiation, encouragement, activity, discussion or negotiation
    with any parties conducted heretofore by OSI or any OSI Representatives with
    respect to any OSI Acquisition Proposal existing on the date hereof.
 
        (iii) Not less than one business day prior to taking any action referred
    to in Section 7.1(a)(i), if OSI intends to participate in any such
    discussions or negotiations or provide any such information to any such
    third party, OSI shall give written notice to CRA of such intended action.
    OSI will promptly notify CRA of such requests of such information or the
    receipt of any OSI Acquisition Proposal, including the identity of the
    person or group engaging in such discussions or negotiations, requesting
    such information or making such OSI Acquisition Proposal, and the material
    terms and conditions of any OSI Acquisition Proposal.
 
                                      A-19
<PAGE>
        (iv) As used in this Agreement, "OSI Acquisition Proposal" means any
    proposal or offer made by a person or group of persons other than a proposal
    or offer by CRA or any of its Affiliates (which person or group has, in the
    good faith determination of the Board of Directors of OSI, the financial
    ability to consummate such proposal or offer), for, or that could be
    reasonably expected to lead to, a tender or exchange offer, a merger,
    consolidation or other business combination involving such person or group
    and OSI or any OSI Significant Subsidiaries or any proposal from any such
    person or group to acquire in any manner a substantial equity interest in,
    or any substantial portion of the assets of, OSI or any OSI Significant
    Subsidiaries. (b) CRA Alternative Proposal.
 
        (i) From and after the date hereof, CRA will not, and will not authorize
    or (to the extent within its control) permit any of its officers, directors,
    employees, agents, Affiliates and other representatives or those of any of
    its Subsidiaries (collectively, "CRA Representatives") to, directly or
    indirectly, solicit or encourage (including by way of providing information)
    any prospective acquiror or the invitation or submission of any inquiries,
    proposals or offers or any other efforts or attempts that constitute, or may
    reasonably be expected to lead, to any CRA Acquisition Proposal (as
    hereinafter defined) from any person or engage in any discussions or
    negotiations with respect thereto or otherwise cooperate with or assist or
    participate in, or facilitate any such proposal; provided, however, that,
    notwithstanding any other provision of this Agreement (i) CRA's Board of
    Directors may take and disclose to the stockholders of CRA a position
    contemplated by Rule 14e-2(a) promulgated under the Exchange Act and (ii)
    following receipt from a third party, without any solicitation, initiation
    or encouragement, directly or indirectly, by CRA or any CRA Representative,
    of a bona fide CRA Acquisition Proposal, (x) CRA may engage in discussions
    or negotiations with such third party and may furnish such third party
    information concerning it, and its business, properties and assets if such
    third party executes a confidentiality agreement in reasonably customary
    form and (y) the Board of Directors of CRA may withdraw, modify or not make
    its recommendation referred to in Section 7.3 or terminate this Agreement in
    accordance with Article 9, but in each case referred to in the foregoing
    clauses (i) and (ii), only to the extent that CRA's Board of Directors shall
    conclude in good faith based on the advice of CRA's outside counsel that
    such action is necessary in order for CRA's Board of Directors to act in a
    manner that is consistent with its fiduciary obligations under applicable
    law.
 
        (ii) CRA shall immediately cease and cause to be terminated any existing
    solicitation, initiation, encouragement, activity, discussion or negotiation
    with any parties conducted heretofore by CRA or any CRA Representatives with
    respect to any CRA Acquisition Proposal existing on the date hereof.
 
        (iii) Not less than one business day prior to taking any action referred
    to in Section 7.1(b)(i), if CRA intends to participate in any such
    discussions or negotiations or provide any such information to any such
    third party, CRA shall give written notice to OSI of such intended action.
    CRA will promptly notify OSI of such requests of such information or the
    receipt of any CRA Acquisition Proposal, including the identity of the
    person or group engaging in such discussions or negotiations, requesting
    such information or making such CRA Acquisition Proposal, and the material
    terms and conditions of any CRA Acquisition Proposal.
 
        (iv) As used in this Agreement, "CRA Acquisition Proposal" means any
    proposal or offer made by a person or group of persons other than a proposal
    or offer by OSI or any of its Affiliates (which person or group has, in the
    good faith determination of the Board of Directors of CRA, the financial
    ability to consummate such proposal or offer), for, or that could be
    reasonably expected to lead to, a tender or exchange offer, a merger,
    consolidation or other business combination involving such person or group
    and CRA or any CRA Significant Subsidiaries or any proposal from any such
    person or group to acquire in any manner a substantial equity interest in,
    or any substantial portion of the assets of, CRA or any CRA Significant
    Subsidiaries.
 
                                      A-20
<PAGE>
    7.2.  INTERIM OPERATIONS.  (a) Prior to the Effective Time, except as set
forth in the OSI Disclosure Letter or as contemplated by any other provision of
this Agreement, unless CRA has consented in writing thereto, OSI:
 
        (i) Shall, and shall cause each of its Significant Subsidiaries to,
    conduct its operations according to their usual, regular and ordinary course
    in substantially the same manner as heretofore conducted;
 
        (ii) Shall use its commercially reasonable efforts, and shall cause each
    of its Significant Subsidiaries to use its commercially reasonable efforts,
    to preserve intact their business organizations and goodwill, keep available
    the services of their respective officers and employees and maintain
    satisfactory relationships with those persons having business relationships
    with them;
 
       (iii) Shall not amend its Certificate of Incorporation or Bylaws or
    comparable governing instruments (other than Bylaw amendments which are not
    material to OSI or to the consummation of the transactions contemplated by
    this Agreement);
 
        (iv) Shall promptly notify CRA of any breach of any representation or
    warranty of OSI of which OSI becomes aware contained herein or any OSI
    Material Adverse Effect;
 
        (v) Shall promptly deliver to CRA true and correct copies of any report,
    statement or schedule filed with the SEC subsequent to the date of this
    Agreement;
 
        (vi) Shall not (w) except pursuant to the conversion of the OSI
    Convertible Notes, the conversion of the Anderson Note, and the exercise of
    options, warrants, conversion rights and other contractual rights existing
    on the date hereof and disclosed pursuant to this Agreement or in the OSI
    Reports, issue any shares of its capital stock, effect any stock split or
    otherwise change its capitalization as it existed on the date hereof, (x)
    grant, confer or award any option, warrant, conversion right or other right
    not existing, on the date hereof to acquire any shares of its capital stock
    (other than the grant of options to acquire an aggregate of up to 15,000
    shares of OSI Common Stock pursuant to the terms of the OSI Stock Option
    Plans at an exercise price of not less than the fair market value of the OSI
    Common Stock on the date of grant) or grant, confer or award any bonuses or
    other forms of cash incentives to any officer, director, or employee except
    consistent with past practice, (y) increase any compensation of its present
    or future officers, directors, or employees (except for normal increases
    consistent with past practice or as required under the written terms of an
    OSI Employment Agreement in effect on or before December 31, 1996); enter
    into any employment agreement with any present or future employee, officer,
    or director, or amend any such agreement in any material respect; grant any
    severance or termination pay to any officer, director or employee other than
    pursuant to existing severance arrangements and policies of OSI or (z) adopt
    any new OSI Plan or amend any existing OSI Plan in any material respect;
 
       (vii) Shall not (i) declare, set aside or pay any dividend or make any
    other distribution or payment with respect to any shares of its capital
    stock or other ownership interests, (ii) directly or indirectly redeem,
    purchase or otherwise acquire any shares of its capital stock or capital
    stock of any of its Subsidiaries, or make any commitment for any such action
    or (iii) split, combine or reclassify any of its capital stock or issue or
    authorize or propose the issuance of any other securities in respect of, in
    lieu of or in substitution for shares of its capital stock;
 
      (viii) Shall not, and shall not permit any of its Subsidiaries to (A)
    sell, lease or otherwise dispose of any of its assets (including capital
    stock of Subsidiaries) except in the ordinary course of business, or (B)
    acquire any business or any substantial portion of the assets of any person
    except as identified in the OSI Disclosure Letter and acquisitions involving
    the payment of consideration by OSI not in excess of $10,000,000 for any
    single acquisition or $25,000,000 in the aggregate (it being understood that
    OSI will give CRA not less than fifteen (15) days prior notice of the
    proposed acquisition of any business or any substantial portion of the
    assets of any person; if such acquisition requires the written consent of
    CRA under this clause (viii), consent shall not be unreasonably withheld;
    and CRA shall be
 
                                      A-21
<PAGE>
    deemed to have given such consent if it does not respond within ten (10)
    days of receipt of the notice contemplated hereby);
 
        (ix) Shall not incur any material amount of indebtedness for borrowed
    money or make any loans, advances or capital contributions to, or
    investments (other than non-controlling investments in the ordinary course
    of business or other investments permitted pursuant to clause (viii) above)
    in, any other person other than a wholly owned Subsidiary, or issue or sell
    any debt securities, other than borrowings under existing lines of credit in
    the ordinary course of business, in each case in an amount exceeding
    $1,000,000;
 
        (x) Shall not, except as previously approved by the Board of Directors
    of OSI and identified to CRA prior to the date hereof, or except in the
    ordinary course of business, make or commit to make capital expenditures
    other than (A) capital expenditures budgeted for the fiscal year ending
    December 31, 1997, and (B) capital expenditures (not otherwise included in
    budgeted capital expenditures referred to in clause (A) above) that may be
    made by OSI in connection with the acquisitions by OSI or its Subsidiaries
    permitted under subsection (viii) above; provided such acquisitions would
    have been permitted under such subsection (viii) if such capital
    expenditures were deemed to be payment of consideration by OSI in connection
    therewith;
 
        (xi) Shall not mortgage or otherwise encumber or subject to any lien any
    properties or assets except as would not be reasonably likely to have an OSI
    Material Adverse Effect;
 
       (xii) Shall not make any change to its accounting (including tax
    accounting) methods, principles or practices, except as may be required by
    generally accepted accounting principles and except, in the case of tax
    accounting methods, principles or practices, in the ordinary course of
    business of OSI or any of its Subsidiaries;
 
      (xiii) Shall not and shall not permit any of its Subsidiaries to, enter
    into any agreement or arrangement with any of their respective Affiliates,
    other than with wholly-owned Subsidiaries of OSI, on terms less favorable to
    OSI or such Subsidiary, as the case may be, than could be reasonably
    expected to have been obtained with an unaffiliated third party on an
    arm's-length basis;
 
       (xiv) Shall, and shall cause its Subsidiaries to, use commercially
    reasonable efforts to maintain with financially responsible insurance
    companies insurance in such amounts and against such risks and losses as are
    customary for companies engaged in their respective businesses; and
 
       (xv) Shall not (i) make or rescind any material express or deemed
    election relating to taxes, unless it is reasonably expected that such
    action will not result in an OSI Material Adverse Effect, (ii) settle or
    compromise any material claim, action, suit, litigation, proceeding,
    arbitration, investigation, audit or controversy relating to taxes, except
    where such settlement or compromise will not result in an OSI Material
    Adverse Effect, or (iii) change in any material respect any of its methods
    or reporting income or deductions for federal income tax purposes from those
    employed in the preparation of its federal income tax returns that have been
    filed for prior taxable years, except as may be required by applicable law
    or except for changes that are reasonably expected not to result in an OSI
    Material Adverse Effect.
 
    (b) Prior to the Effective Time, except as set forth in the CRA Disclosure
Letter or as contemplated by this Agreement, unless OSI has consented in writing
thereto, CRA:
 
        (i) Shall, and shall cause each of its Significant Subsidiaries to,
    conduct its operations according to their usual, regular and ordinary course
    in substantially the same manner as heretofore conducted;
 
        (ii) Shall use its commercially reasonable efforts, and shall cause each
    of its Significant Subsidiaries to use its commercially reasonable efforts,
    to preserve intact their business organizations and goodwill, keep available
    the services of their respective officers and employees and maintain
    satisfactory relationships with those persons having business relationships
    with them;
 
                                      A-22
<PAGE>
       (iii) Shall not amend its Certificate of Incorporation or Bylaws or
    comparable governing instruments (other than Bylaw amendments which are not
    material to CRA or to the consummation of the transactions contemplated by
    this Agreement);
 
        (iv) Shall promptly notify OSI of any breach of any representation or
    warranty of CRA of which CRA becomes aware contained herein or any CRA
    Material Adverse Effect;
 
        (v) Shall promptly deliver to OSI true and correct copies of any report,
    statement or schedule filed with the SEC subsequent to the date of this
    Agreement;
 
        (vi) Shall not (w) except pursuant to the exercise of options, warrants,
    conversion rights and other contractual rights existing on the date hereof
    and disclosed pursuant to this Agreement or in the OSI Reports, issue any
    shares of its capital stock, effect any stock split or otherwise change its
    capitalization as it existed on the date hereof, (x) grant, confer or award
    any option, warrant, conversion right or other right not existing, on the
    date hereof to acquire any shares of its capital stock (other than the grant
    of options to acquire an aggregate of up to 15,000 shares of CRA Common
    Stock pursuant to the terms of the CRA Stock Option Plans at an exercise
    price of not less than the fair market value of the CRA Common Stock on the
    date of grant) existing on the date hereof of CRA's stock option plan) or
    grant, confer or award any bonuses or other forms of cash incentives to any
    officer, director, or employee except consistent with past practice, (y)
    increase any compensation of its present or future officers, directors, or
    employees, (except for normal increases consistent with past practice or as
    required under the written terms of a CRA Employment Agreement in effect on
    or before December 31, 1996); enter into any employment agreement with any
    present or future employee, officer, or director or amend any such agreement
    in any material respect; grant any severance or termination pay to any
    officer, director or employee other than pursuant to existing severance
    arrangements and policies of CRA or (z) adopt any new CRA Plan or amend any
    existing CRA Plan in any material respect;
 
       (vii) Shall not (i) declare, set aside or pay any dividend or make any
    other distribution or payment with respect to any shares of its capital
    stock or other ownership interests, (ii) directly or indirectly redeem,
    purchase or otherwise acquire any shares of its capital stock or capital
    stock of any of its Subsidiaries, or make any commitment for any such action
    or (iii) split, combine or reclassify any of its capital stock or issue or
    authorize or propose the issuance of any other securities in respect of, in
    lieu of or in substitution for shares of its capital stock;
 
      (viii) Shall not, and shall not permit any of its Subsidiaries to (A)
    sell, lease or otherwise dispose of any of its assets (including capital
    stock of Subsidiaries) except in the ordinary course of business, or (B)
    acquire any business or any substantial portion of the assets of any person
    except as identified in the CRA Disclosure Letter and acquisitions involving
    the payment of consideration by CRA not in excess of $10,000,000 for any
    single acquisition or $25,000,000 in the aggregate (it being understood that
    CRA will give OSI not less than fifteen (15) days prior notice of the
    proposed acquisition of any business or any substantial portion of the
    assets of any person; if such acquisition requires the consent of OSI under
    this clause (viii), consent shall not be unreasonably withheld; and OSI
    shall be deemed to have given such consent if it does not respond within ten
    (10) days of receipt of the notice contemplated hereby);
 
        (ix) Shall not incur any material amount of indebtedness for borrowed
    money or make any loans, advances or capital contributions to, or
    investments (other than non-controlling investments in the ordinary course
    of business or other investments permitted pursuant to clause (viii) above),
    in each case in an amount exceeding $1,000,000;
 
        (x) Shall not, except as previously approved by the Board of Directors
    of CRA and identified to OSI prior to the date hereof, or except in the
    ordinary course of business, make or commit to make
 
                                      A-23
<PAGE>
    capital expenditures other than (A) capital expenditures budgeted for the
    fiscal year ending December 31, 1997 and (B) capital expenditures (not
    otherwise included in budgeted capital expenditures referred to in clause
    (A) above) that may be made by CRA in connection with the acquisitions by
    CRA or its Subsidiaries permitted under subsection (viii) above; provided
    such acquisitions would have been permitted under such subsection (viii) if
    such capital expenditures were deemed to be payment of consideration by CRA
    in connection therewith.
 
        (xi) Shall not mortgage or otherwise encumber or subject to any lien any
    properties or assets except as would not be reasonably likely to have a CRA
    Material Adverse Effect;
 
       (xii) Shall not make any change to its accounting (including tax
    accounting) methods, principles or practices, except as may be required by
    generally accepted accounting principles and except, in the case of tax
    accounting methods, principles or practices, in the ordinary course of
    business of CRA or any of its Subsidiaries;
 
      (xiii) Shall not and shall not permit any of its Subsidiaries to, enter
    into any agreement or arrangement with any of their respective Affiliates,
    other than with wholly-owned Subsidiaries of CRA, on terms less favorable to
    CRA or such Subsidiary, as the case may be, than could be reasonably
    expected to have been obtained with an unaffiliated third party on an
    arm's-length basis;
 
       (xiv) Shall, and shall cause its Subsidiaries to, use commercially
    reasonable efforts to maintain with financially responsible insurance
    companies insurance in such amounts and against such risks and losses as are
    customary for companies engaged in their respective businesses; and
 
       (xv) Shall not (i) make or rescind any material express or deemed
    election relating to taxes, unless it is reasonably expected that such
    action will not result in a CRA Material Adverse Effect, (ii) settle or
    compromise any material claim, action, suit, litigation, proceeding,
    arbitration, investigation, audit or controversy relating to taxes, except
    where such settlement or compromise will not result in a CRA Material
    Adverse Effect, or (iii) change in any material respect any of its methods
    or reporting income or deductions for federal income tax purposes from those
    employed in the preparation of its federal income tax returns that have been
    filed for prior taxable years, except as may be required by applicable law,
    or except for changes that are reasonably expected not to result in a CRA
    Material Adverse Effect.
 
    7.3.  MEETINGS OF STOCKHOLDERS.  Each of CRA and OSI will take all action
necessary in accordance with applicable law and its Articles of Organization or
Certificate of Incorporation, as the case may be, and Bylaws to convene a
meeting of its stockholders as promptly as practicable to consider and vote upon
(i) in the case of CRA, the approval of this Agreement, the CRA Merger Agreement
and the CRA Merger and (ii) in the case of OSI, the approval of this Agreement
and the OSI Merger. Subject to the exercise of the fiduciary duties of the
Boards of Directors of CRA and OSI, the Board of Directors of each of CRA and
OSI shall recommend such approval (and shall not revoke or withdraw such
recommendation) and CRA and OSI shall each take all lawful action to solicit
such approval, including, without limitation, timely mailing the Proxy
Statement/Prospectus (as defined in Section 7.7).
 
    7.4.  FILINGS, OTHER ACTION.  (a) Each party hereto shall file or cause to
be filed with the Federal Trade Commission (the "FTC") and the Antitrust
Division of the Department of Justice (the "Antitrust Division") any
notification required to be filed by their respective "ultimate parent"
companies under the HSR Act and the rules and regulations promulgated thereunder
with respect to the transactions contemplated hereby. Such parties will use all
commercially reasonable efforts to make such filings promptly and to respond on
a timely basis to any requests for additional information made by either of such
agencies. Each of the parties hereto agrees to furnish the others with copies of
all correspondence, filings and communications (and memorandum setting forth the
substance thereof) between it and its Affiliates and their respective
representatives, on the one hand, and the FTC, the Antitrust Division or any
other court, governmental, regulatory or administrative agency or commission or
other governmental authority or
 
                                      A-24
<PAGE>
instrumentality, domestic or foreign (a "Governmental Entity"), or members or
their respective staffs, on the other hand, with respect to this Agreement and
the transactions contemplated hereby, other than personal financial information
filed therewith. Each party hereto agrees to furnish the others with such
necessary information and reasonable assistance as such other parties and their
respective affiliates may reasonably request in connection with their
preparation of necessary filings, registrations or submissions of information to
any Governmental Entities, including without limitation any filings necessary
under the provisions of the HSR Act.
 
    (b) Each party hereto shall cooperate and use its reasonable best efforts to
promptly prepare and file all necessary documentation to effect all necessary
application, notices, petitions, filings and other documents, and use all
commercially reasonable efforts to obtain (and will cooperate with each other in
obtaining) any consent, acquiescence, authorization, order or approval of, or
any exemption or nonopposition by, any Governmental Entity required to be
obtained or made by OSI or CRA or any of their respective Significant
Subsidiaries in connection with the Mergers or the taking of any action
contemplated thereby or by this Agreement; and
 
    (c) Subject to the terms and conditions herein provided, including the
exercise of the fiduciary duties of the Boards of Directors of CRA and OSI, the
parties hereto shall use all commercially reasonable efforts to take, or cause
to be taken, all other action and do, or cause to be done, all other things
necessary, proper or appropriate to consummate and make effective the
transactions contemplated by this Agreement.
 
    7.5.  INSPECTION OF RECORDS.  From the date hereof to the Effective Time,
each of OSI and CRA shall (i) allow all designated officers, attorneys,
accountants and other representatives of the other reasonable access at all
reasonable times to the offices, records and files, correspondence, audits and
properties, as well as to all information relating to commitments, contracts,
titles and financial position, or otherwise pertaining to the business and
affairs, of OSI and CRA and their respective Subsidiaries, as the case may be,
(ii) furnish to the other, the other's counsel, financial advisors, auditors and
other authorized representatives such financial and operating data and other
information as such persons may reasonably request and (iii) instruct the
employees, counsel and financial advisors of OSI or CRA, as the case may be, to
cooperate with the other in the other's investigation of the business of it and
its Subsidiaries.
 
    7.6.  PUBLICITY.  The initial press release relating to this Agreement shall
be a joint press release and thereafter OSI and CRA shall, subject to their
respective legal obligations (including requirements of stock exchanges,
quotation or trading systems and other similar regulatory bodies), consult with
each other, and use commercially reasonable efforts to agree upon the text of
any press release, before issuing any such press release or otherwise making
public statements with respect to the transactions contemplated hereby and in
making any filings with any federal or state governmental or regulatory agency
or with any national securities exchange or quotation or trading system with
respect thereto.
 
    7.7.  REGISTRATION STATEMENT.  CRA and OSI shall cooperate and promptly
prepare and Holding Company shall file with the SEC as soon as practicable a
Registration Statement on Form S-4 (the "Form S-4") under the Securities Act,
with respect to the Holding Company Common Stock issuable in the Mergers, a
portion of which Registration Statement shall also serve as the joint proxy
statement with respect to the meetings of the stockholders of OSI and of CRA in
connection with the Mergers (the "Proxy Statement/Prospectus"). The respective
parties will cause the Proxy Statement/Prospectus and the Form S-4 to comply as
to form in all material respects with the applicable provisions of the
Securities Act, the Exchange Act and the rules and regulations thereunder.
Holding Company shall use all commercially reasonable efforts, and CRA and OSI
will cooperate with Holding Company, to have the Form S-4 declared effective by
the SEC as promptly as practicable and to keep the Form S-4 effective as long as
is necessary to consummate the Mergers. Holding Company shall, as promptly as
practicable, provide copies of any written comments received from the SEC with
respect to the Form S-4 to CRA and OSI and advise CRA and OSI of any verbal
comments with respect to the Form S-4 received from the SEC. Holding
 
                                      A-25
<PAGE>
Company shall use its reasonable best efforts to obtain, prior to the effective
date of the Form S-4, all necessary state securities law or "Blue Sky" permits
or approvals required to carry out the transactions contemplated by this
Agreement and will pay all expenses incident thereto. Holding Company agrees
that (i) the S-4 will not, at the time it is filed with the Commission and the
time it becomes effective under the Securities Act, contain any untrue statement
of a material fact or omit to state any material fact required to be stated
therein or necessary to make the statements therein not misleading and (ii) the
Proxy Statement/Prospectus and each amendment or supplement thereto at the time
of mailing thereof and at the time of the respective meetings of stockholders of
OSI and CRA will not include an untrue statement of a material fact or omit to
state a material fact required to be stated therein or necessary to make the
statements therein, in light of the circumstances under which they were made,
not misleading; provided, however, that the foregoing shall not apply to the
extent that any such untrue statement of a material fact or omission to state a
material fact was made by Holding Company in reliance upon and in conformity
with written information concerning CRA or OSI furnished to Holding Company by
CRA or OSI specifically for use in the Proxy Statement/Prospectus. CRA and OSI
each agrees that the written information provided by it for inclusion in the S-4
and each amendment or supplement thereto, at the time it is filed with the
Commission and the time it becomes effective under the Securities Act, will not
include an untrue statement of a material fact or omit to state a material fact
required to be stated therein or necessary to make the statements therein not
misleading. CRA and OSI each agrees that the written information provided by it
for inclusion in the Proxy Statement/Prospectus and each amendment or supplement
thereto, at the time of mailing thereof, and at the time of the respective
meetings of stockholders of OSI and CRA will not include an untrue statement of
a material fact or omit to state a material fact required to be stated therein
or necessary to make the statements therein, in light of the circumstances under
which they were made, not misleading. No amendment or supplement to the Proxy
Statement/Prospectus will be made by Holding Company without the approval of CRA
and OSI. Holding Company will advise CRA and OSI, promptly after it receives
notice thereof, of the time when the Form S-4 has become effective or any
supplement or amendment has been filed, the issuance of any stop order, the
suspension of the qualification of Holding Company Common Stock issuable in
connection with the Mergers for offering or sale in any jurisdiction, or any
request by the SEC for amendment of the Proxy Statement/Prospectus or the Form
S-4 or comments thereon and responses thereto or requests by the SEC for
additional information.
 
    7.8.  LISTING APPLICATION.  Holding Company shall promptly prepare and
submit to the Nasdaq National Market a listing application covering the shares
of Holding Company Common Stock issuable in the Mergers, and shall use
commercially reasonable efforts to obtain, prior to the Effective Time, approval
for the quotation, of such Holding Company Common Stock, subject to official
notice of issuance, on the Nasdaq National Market.
 
    7.9.  FURTHER ACTION.  Each party hereto shall, subject to the fulfillment
at or before the Effective Time of each of the conditions of performance set
forth herein or the waiver thereof, perform such further acts and execute such
documents as may be reasonably required to effect the Mergers, including in the
case of CRA and OSI causing their designees on the Holding Company Board of
Directors to cause Holding Company to perform such acts and execute such
documents.
 
    7.10.  AFFILIATE LETTERS.  At least 30 days prior to the Closing Date, CRA
and OSI shall deliver to Holding Company a list of names and addresses of those
persons who were, in CRA's and OSI's reasonable judgment, at the record date for
its stockholders' meeting to approve the Mergers, "affiliates" (each such
person, an "Affiliate") of CRA or OSI within the meaning of Rule 145 of the
rules and regulations promulgated under the Securities Act. OSI shall use all
commercially reasonable efforts to deliver or cause to be delivered to Holding
Company, prior to the Closing Date, from each of the Affiliates of OSI
identified in the foregoing list, an Affiliate Letter in the form attached
hereto as Exhibit E. CRA shall use all commercially reasonable efforts to
deliver or cause to be delivered to Holding Company, prior to the Closing Date,
from each of the Affiliates of CRA identified in the foregoing list, an
Affiliate Letter in the
 
                                      A-26
<PAGE>
form attached hereto as Exhibit E. Holding Company shall be entitled to place
legends as specified in such Affiliate Letters on the certificates evidencing
any Holding Company Common Stock to be received by such Affiliates pursuant to
the terms of this Agreement, and to issue appropriate stop transfer instructions
to the transfer agent for the Holding Company Common Stock, consistent with the
terms of such Affiliate Letters.
 
    7.11.  EXPENSES.  Whether or not the Mergers are consummated, all costs and
expenses incurred in connection with this Agreement and the transactions
contemplated hereby shall be paid by the party incurring such expenses except as
expressly provided herein and except that (a) the filing fee in connection with
the HSR Act filing, (b) the filing fee in connection with the filing of the Form
S-4 or Proxy Statement/ Prospectus with the SEC, (c) the reasonable expenses of
Holding Company and (d) the expenses incurred in connection with printing and
mailing the Form S-4 and the Proxy Statement/Prospectus, shall be shared equally
by OSI and CRA. OSI and CRA each agree to pay one-half of any such expenses
promptly upon written request therefor by Holding Company or by any other
person, including OSI or CRA, paying on behalf of, or providing credit with
respect thereto to, Holding Company.
 
    7.12.  INSURANCE; INDEMNITY.  (a) From and after the Effective Time, Holding
Company shall indemnify, defend and hold harmless to the fullest extent that CRA
or OSI would have been permitted under applicable law each person who is now, or
has been at any time prior to the date hereof, an officer or director of CRA or
OSI (individually, an "Indemnified Party" and collectively, the "Indemnified
Parties"), against all losses, claims, damages, liabilities, costs or expenses
(including attorneys' fees), judgments, fines, penalties and amounts paid in
settlement in connection with any claim, action, suit, proceeding or
investigation arising out of or pertaining to acts or omissions, or alleged acts
or omissions, by them in their capacities as such occurring at or prior to the
Effective Time. In the event of any such claim, action, suit, proceeding, or
investigation (an "Action"), (i) any Indemnified Party wishing to claim
indemnification shall promptly notify Holding Company thereof, (ii) Holding
Company shall pay the reasonable fees and expenses of counsel selected by the
Indemnified Party, which counsel shall be reasonably acceptable to Holding
Company, in advance of the final disposition of any such Action to the full
extent permitted by applicable law, upon receipt of any undertaking required by
applicable law, and (iii) Holding Company will cooperate in the defense of any
such matter; provided, however, that Holding Company shall not be liable for any
settlement effected without its written consent and provided, further, that
Holding Company shall not be obligated pursuant to this Section to pay the fees
and disbursements of more than one counsel for all Indemnified Parties in any
single Action except to the extent that, in the opinion of counsel for the
Indemnified Parties, two or more of such Indemnified Parties have conflicting
interests in the outcome of such action.
 
    (b) Holding Company shall keep in effect, and shall cause the surviving
corporation of the CRA Merger to keep in effect, provisions in its Articles or
Certificate of Incorporation or Organization and Bylaws providing for
exculpation of director and officer liability and its indemnification of the
Indemnified Parties to the fullest extent permitted under applicable law, which
provisions shall not be amended except as required by applicable law or except
to make changes permitted by law that would enlarge the Indemnified Parties'
rights of exculpation and indemnification.
 
    (c) For a period of six years after the Effective Time, Holding Company
shall cause to be maintained officers' and directors' liability insurance
covering the Indemnified Parties who are currently covered, in their capacities
as officers and directors, by CRA's or OSI's existing officers' and directors'
liability insurance policies on terms materially no less advantageous to the
Indemnified Parties than such existing insurance; provided, however, that
Holding Company shall not be required in order to maintain or procure such
coverage to pay an annual premium for either CRA or OSI in excess of one and
one-half times the current annual premium paid by OSI for its existing coverage
(the "Cap") (which current annual premium is approximately $110,000); and
provided, further, that if equivalent coverage cannot be obtained for CRA or
OSI, or can be obtained only by paying an annual premium in excess of the Cap,
Holding Company shall
 
                                      A-27
<PAGE>
only be required to obtain as much coverage for CRA or OSI as can be obtained by
paying an annual premium equal to such Cap.
 
    (d) In the event that Holding Company or any of its successors or assigns
(i) consolidates with or merges into any other person and shall not be the
continuing or surviving corporation or entity of such consolidation or merger or
(ii) transfers all or substantially all of its properties and assets to any
person, then, in each such case, proper provisions shall be made so that the
successors and assigns of Holding Company shall assume the obligations set forth
in this Section 7.12.
 
    (e) The provisions of this Section shall survive the consummation of the
Mergers and expressly are intended to benefit each of the Indemnified Parties.
The foregoing provisions of this Section 7.12 shall not limit or impair the
rights of the Indemnified Parties arising under any indemnification or other
agreements to which they are a party, the charter, bylaws or other
organizational documents of CRA and OSI and their respective Subsidiaries or
applicable laws.
 
    7.13.  TAKEOVER STATUTE.  If any "fair price", "moratorium", "control share
acquisition" or other form of antitakeover statute or regulation shall become
applicable to the transactions contemplated hereby, CRA and OSI and the members
of the Boards of Directors of CRA and OSI shall grant such approvals and take
such actions as are reasonably necessary so that the transactions contemplated
hereby may be consummated as promptly as practicable on the terms contemplated
hereby and otherwise act to eliminate or minimize the effects of such statute or
regulation on the transactions contemplated hereby.
 
    7.14.  CONDUCT OF BUSINESS BY HOLDING COMPANY AND CRA MERGER SUB PENDING THE
MERGERS.  Prior to the Effective Time and subject to any applicable regulatory
approvals, CRA and OSI shall cause Holding Company and CRA Merger Sub to (a)
perform their respective obligations hereunder and under this Agreement and the
Merger Agreements in accordance with the terms hereof and thereof and take all
other actions necessary or appropriate for the consummation of the transactions
contemplated hereby and thereby, (b) not incur directly or indirectly any
liabilities or obligations except those incurred in connection with the
consummation of this Agreement and the Merger Agreements and the transactions
contemplated hereby and thereby, (c) not engaged directly or indirectly in any
business or activities of any type or kind whatsoever and not enter into any
agreements or arrangements with any person or entity, or be subject to or be
bound by any obligation or undertaking which is not contemplated by this
Agreement or the Merger Agreements and (d) not create, grant or suffer to exist
any lien upon their respective properties or assets which would attach to any
properties or assets of CRA or OSI after the Effective Time.
 
    7.15.  EMPLOYEE BENEFITS.  Immediately following the Effective Time, Holding
Company will cause employee benefit plans to be in effect for the benefit of
CRA's and OSI's employees that are reasonably comparable in the aggregate to the
employee benefit plans that were in effect immediately prior to the Effective
Time.
 
    7.16.  CONVEYANCE TAXES.  OSI and CRA shall cooperate in the preparation,
execution and filing of all returns, questionnaires, applications or other
documents regarding any real property transfer or gains, sales, use, transfer,
value added, stock transfer and stamp taxes, any transfer, recording,
registration and other fees, and any similar taxes which become payable in
connection with the transactions contemplated by this Agreement that are
required or permitted to be filed on or before the Effective Time.
 
    7.17  INCENTIVE PLAN.  Holding Company shall promptly adopt an executive
long term incentive plan reasonably acceptable to both CRA and OSI.
 
                                      A-28
<PAGE>
                                   ARTICLE 8
 
                                   CONDITIONS
 
    8.1.  CONDITIONS TO EACH PARTY'S OBLIGATION TO EFFECT THE MERGERS.  The
respective obligation of each party to effect the Mergers shall be subject to
the fulfillment at or prior to the Closing Date of the following conditions:
 
    (a) This Agreement and the transactions contemplated hereby shall have been
approved in the manner required by applicable law or by the applicable
regulations of the Nasdaq National Market, any stock exchange or other
regulatory body, as the case may be, by the holders of the issued and
outstanding shares of capital stock of OSI and CRA, respectively.
 
    (b) The waiting period applicable to the consummation of the Mergers under
the HSR Act shall have expired or been terminated and all filings required to be
made prior to the Effective Time with, and all consents, approvals, permits and
authorizations required to be obtained prior to the Effective Time from, any
Governmental Entity in connection with the execution and delivery of this
Agreement and the consummation of the transactions contemplated hereby shall
have been made or obtained (as the case may be), except for such consents,
approvals, permits or authorizations the failure of which to be obtained would
not, in the aggregate, be reasonably likely to have, a Material Adverse Effect
on Holding Company (assuming the Mergers have taken place) or to materially
adversely affect the consummation of the Mergers, and no such consent, approval,
permit or authorization shall impose terms or conditions that would have, or
would be reasonably likely to have, a Material Adverse Effect on Holding Company
(assuming the Mergers have taken place).
 
    (c) No temporary restraining order, preliminary or permanent injunction or
other order issued by any court of competent jurisdiction, no order of any
Governmental Entity having jurisdiction over any party hereto, and no other
legal restraint or prohibition shall be in effect (an "Injunction") preventing
or making illegal the consummation of the Mergers. In the event any such
Injunction shall have been issued, each party agrees to use its reasonable best
efforts to have any such Injunction lifted.
 
    (d) The Form S-4 shall have become effective and shall be effective at the
Effective Time, and no stop order suspending effectiveness of the Form S-4 shall
have been issued, no action, suit, proceeding or investigation by the SEC to
suspend the effectiveness thereof shall have been initiated and be continuing
or, to the knowledge of CRA or OSI, threatened.
 
    (e) All consents, authorizations, orders and approvals of (or filings or
registrations with) any governmental commission, board or other regulatory body
required in connection with the execution, delivery and performance of this
Agreement shall have been obtained or made, except for filings in connection
with the Mergers and any other documents required to be filed after the
Effective Time and except where the failure to have obtained or made any such
consent, authorization, order, approval, filing or registration would not have a
material adverse effect on the business, results of operations or financial
condition of CRA and OSI (and their respective Subsidiaries), taken as a whole,
following the Effective Time.
 
    (f) The Holding Company Common Stock to be issued to CRA and OSI
stockholders in connection with the Mergers shall have been approved for
quotation on the Nasdaq National Market, subject only to official notice of
issuance.
 
    8.2.  CONDITIONS TO OBLIGATION OF OSI TO EFFECT THE MERGERS.  The obligation
of OSI to effect the Mergers shall be subject to the fulfillment at or prior to
the Closing Date of the following conditions:
 
    (a) CRA shall have performed in all material respects its agreements
contained in this Agreement required to be performed on or prior to the Closing
Date, the representations and warranties of CRA contained in this Agreement and
in any document delivered in connection herewith shall be true and correct in
all respects as of the Closing Date (other than those representations and
warranties which
 
                                      A-29
<PAGE>
contain qualifications as to materiality, which shall be true and correct in all
respects as of the Closing Date), except (i) for changes specifically permitted
by this Agreement and (ii) that those representations and warranties which
address matters only as of a particular date shall remain true and correct in
all material respects as of such date (other than those representations and
warranties which contain qualifications as to materiality, which shall be true
and correct in all respects as of such date), and OSI shall have received a
certificate of the President or a Vice President of CRA, dated the Closing Date,
certifying to such effect.
 
    (b) OSI and Holding Company shall have received the opinion of Vinson &
Elkins L.L.P., special counsel to OSI and Holding Company, based upon reasonably
requested representation letters and dated the Closing Date, to the effect that
the OSI Merger will be treated as a reorganization governed by Section 368(a) of
the Code; and that OSI will not recognize gain or income in the OSI Merger.
 
    (c) From the date of this Agreement through the Effective Time, there shall
not have occurred any change in the financial condition, business or operations
of CRA and its Subsidiaries, taken as a whole, that would have or would be
reasonably likely to have a CRA Material Adverse Effect.
 
    (d) Holders of not more than 5% of the CRA Common Stock outstanding
immediately preceding the Effective Time shall have perfected appraisal rights
under applicable law.
 
    (e) At the Closing, OSI shall have received an opinion, dated the Closing
Date, from CRA's independent auditors, Arthur Andersen, L.L.P., to the effect
that the business combination to be effected by the Mergers would be properly
accounted for as a pooling-of-interests.
 
    (f) The opinion of DLJ referred to in Section 5.15 herein shall have been
reissued at the time of mailing the Proxy Statement/Prospectus and shall not
have been withdrawn or materially modified by DLJ in a manner adverse to OSI's
stockholders.
 
    8.3.  CONDITIONS TO OBLIGATION OF CRA TO EFFECT THE MERGERS.  The obligation
of CRA to effect the Mergers shall be subject to the fulfillment at or prior to
the Closing Date of the following conditions:
 
    (a) OSI shall have performed in all material respects its agreements
contained in this Agreement required to be performed on or prior to the Closing
Date, the representations and warranties of OSI contained in this Agreement and
in any document delivered in connection herewith shall be true and correct in
all material respects as of the Closing Date (other than those representations
and warranties which contain qualifications as to materiality, which shall be
true and correct in all respects as of the Closing Date), except (i) for changes
specifically permitted by this Agreement and (ii) that those representations and
warranties which address matters only as of a particular date shall remain true
and correct in all material respects as of such date (other than those
representations and warranties which contain qualifications as to materiality,
which shall be true and correct in all respects as of such date), and CRA shall
have received a certificate of the President or Vice President of OSI, dated the
Closing Date, certifying to such effect.
 
    (b) CRA shall have received the opinion of Hutchins, Wheeler & Dittmar,
special counsel to CRA, based upon reasonably requested representation letters
and dated the Closing Date, to the effect that the CRA Merger will be treated as
a transfer of property to Holding Company by holders of CRA Common Stock
governed by Section 351(a) of the Code or a reorganization governed by Section
368(a) of the Code or both; and OSI and Holding Company shall have received the
opinion of Vinson & Elkins LLP described in Section 8.2(b) of this Agreement.
 
    (c) From the date of this Agreement through the Effective Time, there shall
not have occurred any change in the financial condition, business or operations
of OSI and its Subsidiaries, taken as a whole, that would have or would be
reasonably likely to have an OSI Material Adverse Effect.
 
    (d) Holders of not more than 5% of the OSI Common Stock outstanding
immediately preceding the Effective Time shall have perfected appraisal rights
under applicable law.
 
                                      A-30
<PAGE>
    (e) At the Closing, CRA shall have received an opinion, dated the Closing
Date, from OSI's independent auditors, Arthur Andersen, L.L.P., to the effect
that the business combination to be effected by the Mergers would be properly
accounted for as a pooling-of-interests.
 
    (f) The opinion of Alex. Brown & Sons Incorporated referred to in Section
6.15 herein shall have been reissued at the time of mailing the Proxy
Statement/Prospectus and shall not have been withdrawn or materially modified by
Alex. Brown & Sons Incorporated in a manner adverse to CRA's stockholders.
 
                                   ARTICLE 9
 
                                  TERMINATION
 
    9.1.  TERMINATION BY MUTUAL CONSENT.  This Agreement may be terminated and
the Mergers may be abandoned at any time prior to the Effective Time, before or
after the approval of this Agreement by the stockholders of CRA or OSI, by the
mutual written consent of CRA and OSI.
 
    9.2.  TERMINATION BY EITHER CRA OR OSI.  This Agreement may be terminated
and the Mergers may be abandoned by action of the Board of Directors of either
CRA or OSI if (a) the Mergers shall not have been consummated by October 31,
1997, or (b) the approval of OSI's stockholders required by Section 8.1(a) shall
not have been obtained at a meeting duly convened therefor or at any adjournment
thereof, or (c) the approval of CRA's stockholders required by Section 8.1(a)
shall not have been obtained at a meeting duly convened therefor or at any
adjournment thereof, or (d) a United States federal or state court of competent
jurisdiction or United States federal or state governmental, regulatory or
administrative agency or commission shall have issued an order, decree or ruling
or taken any other action permanently restraining, enjoining or otherwise
prohibiting the transactions contemplated by this Agreement and such order,
decree, ruling or other action shall have become final and non-appealable;
provided, that the party seeking to terminate this Agreement pursuant to this
clause (d) shall have used all commercially reasonable efforts to remove such
injunction, order or decree; and provided, in the case of a termination pursuant
to clause (a) above, that the terminating party shall not have breached in any
material respect its obligations under this Agreement in any manner that shall
have proximately contributed to the failure to consummate the Mergers by October
31, 1997.
 
    9.3.  TERMINATION BY OSI.  This Agreement may be terminated and the Mergers
may be abandoned at any time prior to the Effective Time, before or after the
adoption and approval by the stockholders of OSI referred to in Section 8.1(a),
by action of the Board of Directors of OSI, if (a) in the exercise of its good
faith judgment as to fiduciary duties to its stockholders imposed by law, as
advised by outside counsel, the Board of Directors of OSI determines that such
termination is required by reason of an OSI Alternative Proposal being made;
provided that OSI shall notify CRA promptly of its intention to terminate this
Agreement or enter into a definitive agreement with respect to any OSI
Alternative Proposal, but in no event shall notice be given less than one full
business day prior to the public announcement of OSI's termination of this
Agreement; or (b) there has been a breach by CRA of any representation or
warranty contained in this Agreement which would have or would be reasonably
likely to have a CRA Material Adverse Effect; or (c) there has been a material
breach of any of the covenants or agreements set forth in this Agreement on the
part of CRA, which breach is not curable or, if curable, is not cured within 30
days after written notice of such breach is given by OSI to CRA; or (d) the
Board of Directors of CRA shall have withdrawn or modified in a manner
materially adverse to OSI its approval or recommendation of this Agreement or
the Mergers. Notwithstanding the foregoing, OSI's ability to terminate this
Agreement pursuant to this Section 9.3 is conditioned upon the prior payment by
OSI of any amount owed by it pursuant to Section 9.5(a).
 
    9.4  TERMINATION BY CRA.  This Agreement may be terminated and the Mergers
may be abandoned at any time prior to the Effective Time, before or after the
approval by the stockholders of CRA referred to in Section 8.1(a), by action of
the Board of Directors of CRA, if (a) in the exercise of its good faith judgment
as to fiduciary duties to its stockholders imposed by law, as advised by outside
counsel, the Board
 
                                      A-31
<PAGE>
of Directors of CRA determines that such termination is required by reason of a
CRA Alternative Proposal being made; provided that CRA shall notify OSI promptly
of its intention to terminate this Agreement or enter into a definitive
agreement with respect to any CRA Alternative Proposal, but in no event shall
notice be given less than one full business day prior to the public announcement
of CRA's termination of this Agreement; or (b) there has been a breach by OSI of
any representation or warranty contained in this Agreement which would have or
would be reasonably likely to have an OSI Material Adverse Effect; or (c) there
has been a material breach of any of the covenants or agreements set forth in
this Agreement on the part of OSI, which breach is not curable or, if curable,
is not cured within 30 days after written notice of such breach is given by CRA
to OSI; or (d) the Board of Directors of OSI shall have withdrawn or modified in
a manner materially adverse to CRA its approval or recommendation of this
Agreement or the Mergers. Notwithstanding the foregoing, CRA's ability to
terminate this Agreement pursuant to this Section 9.4 is conditioned upon the
prior payment by CRA of any amount owed by it pursuant to Section 9.5(b).
 
    9.5.  EFFECT OF TERMINATION AND ABANDONMENT.  (a) In the event that any
person shall have made an OSI Alternative Proposal for OSI and thereafter this
Agreement is terminated pursuant to Section 9.3(a) or Section 9.4(d), then OSI
shall pay to CRA a fee of $10 million, which amount shall be payable by wire
transfer of same day funds either on the date contemplated in the last sentence
of 9.3 if applicable or, otherwise, within two business days after such amount
becomes due. OSI acknowledges that the agreements contained in this Section
9.5(a) are an integral part of the transactions contemplated by this Agreement,
and that, without these agreements, CRA would not enter into this Agreement;
accordingly, if OSI fails to properly pay the amount due pursuant to this
Section 9.5(a) and, in order to obtain such payment, CRA commences a suit which
results in a judgment against OSI for the fee set forth in this Section 9.5(a),
OSI shall pay to CRA its costs and expenses (including attorneys' fees) in
connection with such suit, together with interest in the amount of the fee at
the rate of 12% per annum.
 
    (b) In the event that any person shall have made a CRA Alternative Proposal
for CRA and thereafter this Agreement is terminated pursuant to Section 9.4(a)
or 9.3(d), then CRA shall pay to OSI a fee of $10 million, which amount shall be
payable by wire transfer of same day funds either on the date contemplated in
the last sentence of 9.4 if applicable or, otherwise, within two business days
after such amount becomes due. CRA acknowledges that the agreements contained in
this Section 9.5(b) are an integral part of the transactions contemplated by
this Agreement, and that, without these agreements, OSI would not enter into
this Agreement; accordingly, if CRA fails to properly pay the amount due
pursuant to this Section 9.5(b) and, in order to obtain such payment, OSI
commences a suit which results in a judgment against CRA for the fee set forth
in this Section 9.5(b), CRA shall pay to OSI its costs and expenses (including
attorneys' fees) in connection with such suit, together with interest in the
amount of the fee at the rate of 12% per annum.
 
    (c) In the event of termination of this Agreement and the abandonment of the
Mergers pursuant to this Article 9, all obligations of the parties hereto shall
terminate, except the obligations of the parties pursuant to this Section 9.5
and Section 7.11 and except for the provisions of Article 10. Moreover, in the
event of termination of this Agreement pursuant to Section 9.3 or 9.4, nothing
herein shall prejudice the ability of the non-breaching party from seeking
damages from any other party for any breach of this Agreement, including without
limitation, attorneys' fees and the right to pursue any remedy at law or in
equity.
 
    9.6.  EXTENSION, WAIVER.  At any time prior to the Effective Time, any party
hereto, by action taken by its Board of Directors, may, to the extent legally
allowed, (a) extend the time for the performance of any of the obligations or
other acts of the other parties hereto, (b) waive any inaccuracies in the
representations and warranties made to such party contained herein or in any
document delivered pursuant hereto and (c) waive compliance with any of the
agreements or conditions for the benefit of such party contained herein. Any
agreement on the part of a party hereto to any such extension or waiver shall be
valid only if set forth in an instrument in writing signed on behalf of such
party.
 
                                      A-32
<PAGE>
                                   ARTICLE 10
 
                               GENERAL PROVISIONS
 
    10.1.  NONSURVIVAL OF REPRESENTATIONS, WARRANTIES AND AGREEMENTS.  All
representations, warranties and agreements in this Agreement or in any
instrument delivered pursuant to this Agreement shall be deemed to the extent
expressly provided herein to be conditions to the Mergers and shall not survive
the Mergers, provided, however, that the agreements contained in Article 4,
Section 7.11, Section 7.12, Section 7.15 and this Article 10 shall survive the
Mergers and Sections 7.11 and 9.5 shall survive termination.
 
    10.2.  NOTICES.  Any notice or communication required or permitted hereunder
shall be in writing and either delivered personally, telegraphed or telecopied
or sent by next day delivery by a nationally recognized overnight delivery
service or by certified or registered mail, postage prepaid, and shall be deemed
to be given, dated and received (i) when so delivered personally, (ii) upon
receipt of an appropriate electronic answerback or confirmation when so
delivered by telegraph or telecopy (to such number specified below or another
number or numbers as such person may subsequently designate by notice hereunder)
or (iii) one business day after sending by overnight delivery, and five business
days after the date of mailing by certified or registered mail, to the following
address or to such other address or addresses as such person may subsequently
designate by notice given hereunder, if so delivered by mail:
 
If to CRA:
CRA Managed Care, Inc.
312 Union Wharf
Boston, Massachusetts 02109
Attention: Chairman
Telecopier No.: (617) 720-1259
 
With copies to:
Hutchins, Wheeler & Dittmar
A Professional Corporation
101 Federal Street
Boston, MA 02110
Attention: James Westra, Esq.
Telecopier No.: (617) 951-1295
 
If to OSI:
OccuSystems, Inc.
3010 LBJ Freeway
Suite 400
Dallas, TX 75234
Attention: General Counsel
Telecopier No.: (972) 243-7540
 
                                      A-33
<PAGE>
With copies to:
Vinson & Elkins L.L.P.
2001 Ross Avenue
Suite 3700
Dallas, TX 75201
Attention: Jeffrey A. Chapman
Telecopier No.: (214) 220-7716
 
If to Holding Company:
Concentra Managed Care, Inc.
c/o CRA in accordance with the provisions
of this Section 10.2 and to
Concentra Managed Care, Inc.,
c/o OSI in accordance with the provisions
of this Section 10.2 or to such other address as any party shall specify by
written notice so given.
 
    10.3.  ASSIGNMENT; BINDING EFFECT.  Neither this Agreement nor any of the
rights, interests or obligations hereunder shall be assigned by any of the
parties hereto (whether by operation of law or otherwise) without the prior
written consent of the other parties. Subject to the preceding sentence, this
Agreement shall be binding upon and shall inure to the benefit of the parties
hereto and their respective successors and assigns. Notwithstanding anything
contained in this Agreement to the contrary, except for the provisions of
Section 7.12 and Section 7.15 nothing in this Agreement, expressed or implied,
is intended to confer on any person other than the parties hereto or their
respective heirs, successors, executors, administrators and assigns any rights,
remedies, obligations or liabilities under or by reason of this Agreement.
 
    10.4.  ENTIRE AGREEMENT.  This Agreement, the Exhibits, OSI Disclosure
Letter, CRA Disclosure Letter, the Confidentiality Agreement dated March 19,
1997, between OSI and CRA (except that the "standstill" provisions set forth in
such Confidentiality Agreement are hereby deemed to be superseded by Section 9
of each of the CRA Stock Option Agreement and the OSI Stock Option Agreement),
and any documents delivered by the parties in connection herewith constitute the
entire agreement among the parties with respect to the subject matter hereof and
supersede all prior agreements and understandings among the parties with respect
thereto. No addition to or modification of any provision of this Agreement shall
be binding upon any party hereto unless made in writing and signed by all
parties hereto.
 
    10.5.  AMENDMENT.  This Agreement may be amended by the parties hereto, by
action taken by their respective Boards of Directors, at any time before or
after approval of matters presented in connection with Mergers by the
stockholders of OSI and CRA, but after any such stockholder approval, no
amendment shall be made which by law requires the further approval of
stockholders without obtaining such further approval. This Agreement may not be
amended except by an instrument in writing signed on behalf of each of the
parties hereto.
 
    10.6.  GOVERNING LAW.  This Agreement shall be governed by and construed in
accordance with the laws of Delaware without regard to its rules of conflict of
laws, except that the provisions of Article 2 and Article 4 with respect to the
CRA Merger shall be governed by and construed in accordance with the laws of the
Commonwealth of Massachusetts.
 
    10.7.  COUNTERPARTS.  This Agreement may be executed by the parties hereto
in separate counterparts, each of which when so executed and delivered shall be
an original, but all such counterparts shall together constitute one and the
same instrument. Each counterpart may consist of a number of copies hereof each
signed by less than all, but together signed by all of the parties hereto.
 
                                      A-34
<PAGE>
    10.8.  HEADINGS.  Headings of the Articles and Sections of this Agreement
are for the convenience of the parties only, and shall be given no substantive
or interpretive effect whatsoever.
 
    10.9.  INTERPRETATION.  In this Agreement, unless the context otherwise
requires, words describing the singular number shall include the plural and vice
versa, and words denoting any gender shall include all genders and words
denoting natural persons shall include corporations and partnerships and vice
versa.
 
    10.10.  WAIVERS.  Except as provided in this Agreement, no action taken
pursuant to this Agreement, including, without limitation, any investigation by
or on behalf of any party, shall be deemed to constitute a waiver by the party
taking such action of compliance with any representations, warranties, covenants
or agreements contained in this Agreement. The waiver by any party hereto of a
breach of any provision hereunder shall not operate or be construed as a waiver
of any prior or subsequent breach of the same or any other provision hereunder.
 
    10.11.  INCORPORATION OF EXHIBITS.  The OSI Disclosure Letter, CRA
Disclosure Letter and all Exhibits and Schedules attached hereto and referred to
herein are hereby incorporated herein and made a part hereof for all purposes as
if fully set forth herein.
 
    10.12.  SEVERABILITY.  Any term or provision of this Agreement which is
invalid or unenforceable in any jurisdiction shall, as to that jurisdiction, be
ineffective to the extent of such invalidity or unenforceability without
rendering invalid or unenforceable the remaining terms and provisions of this
Agreement or affecting the validity or enforceability of any of the terms or
provisions of this Agreement in any other jurisdiction. If any provision of this
Agreement is so broad as to be unenforceable, the provision shall be interpreted
to be only so broad as is enforceable.
 
    10.13.  ENFORCEMENT OF AGREEMENT.  The parties hereto agree that irreparable
damage would occur in the event that any of the provisions of this Agreement was
not performed in accordance with its specific terms or was otherwise breached.
It is accordingly agreed that the parties shall be entitled to an injunction or
injunctions to prevent breaches of this Agreement and to enforce specifically
the terms and provisions hereof in any Federal or state court located in the
State of Delaware, this being in addition to any other remedy to which they are
entitled at law or in equity.
 
    10.14.  SUBSIDIARIES.  As used in this Agreement, the word "Subsidiary" when
used with respect to any party means any corporation or other organization,
whether incorporated or unincorporated, of which such party directly or
indirectly owns or controls at least a majority of the securities or other
interests having by their terms ordinary voting power to elect a majority of the
board of directors or others performing similar functions with respect to such
corporation or other organization, or any organization of which such party is a
general partner. When a reference is made in this Agreement to Significant
Subsidiaries, the words "Significant Subsidiaries" shall refer to Subsidiaries
(as defined above) which constitute "significant subsidiaries" under Rule 405
promulgated by the SEC under the Securities Act.
 
               [Remainder of this Page Intentionally Left Blank]
 
                                      A-35
<PAGE>
    IN WITNESS WHEREOF, the parties have executed this Agreement and caused the
same to be duly delivered on their behalf on the day and year first written
above.
 
                                CRA MANAGED CARE, INC.
 
                                By:             /s/ DONALD J. LARSON
                                     -----------------------------------------
                                       PRESIDENT AND CHIEF EXECUTIVE OFFICER
 
                                OCCUSYSTEMS, INC.
 
                                By:             /s/ JOHN K. CARLYLE
                                     -----------------------------------------
                                        CHAIRMAN AND CHIEF EXECUTIVE OFFICER
 
                                CONCENTRA MANAGED CARE, INC.
 
                                By:             /s/ JOHN K. CARLYLE
                                     -----------------------------------------
                                                      CHAIRMAN
 
                                      A-36
<PAGE>
                                  SCHEDULE 1.2
                                       TO
                      AGREEMENT AND PLAN OF REORGANIZATION
 
                 DIRECTORS AND OFFICERS OF THE HOLDING COMPANY
 
                                   DIRECTORS
 
                                Donald J. Larson
 
                                John K. Carlyle
 
                                    OFFICERS
 
<TABLE>
<S>                            <C>
John K. Carlyle                Chairman
Donald J. Larson               President and Chief Executive Officer
John A. McCarthy               Executive Vice President--Managed Care Services
Richard A. Parr II             Executive Vice President, General Counsel, and Secretary
Joseph F. Pesce                Executive Vice President, Chief Financial Officer, and
                                 Treasurer
Daniel J. Thomas               Executive Vice President--Practice Management Services
W. Tom Fogarty, M.D.           Senior Vice President and Chief Medical Officer
Peter R. Gates                 Senior Vice President--Marketing and Sales
James M. Greenwood             Senior Vice President--Corporate Development
</TABLE>
 
                                      A-37
<PAGE>
                                SCHEDULE 3.1(A)
                                       TO
                      AGREEMENT AND PLAN OF REORGANIZATION
 
              DIRECTORS OF THE SURVIVING CORPORATION OF CRA MERGER
 
                                Donald J. Larson
 
                                John A. McCarthy
 
                                Joseph F. Pesce
 
                                      A-38
<PAGE>
                                SCHEDULE 3.1(B)
                                       TO
                      AGREEMENT AND PLAN OF REORGANIZATION
 
                         DIRECTORS OF OCCUCENTERS, INC.
 
                                Donald J. Larson
                                Joseph F. Pesce
                                Daniel J. Thomas
 
                                      A-39
<PAGE>
                                SCHEDULE 3.2(A)
                                       TO
                      AGREEMENT AND PLAN OF REORGANIZATION
 
            OFFICERS OF THE SURVIVING CORPORATION OF THE CRA MERGER
 
<TABLE>
<S>                            <C>
John K. Carlyle                Chairman
Donald J. Larson               President and Chief Executive Officer
John A. McCarthy               Executive Vice President--Managed Care Services
Richard A. Parr II             Executive Vice President, General Counsel, and Secretary
Joseph F. Pesce                Executive Vice President, Chief Financial Officer, and
                                 Treasurer
Peter R. Gates                 Senior Vice President--Marketing and Sales
James M. Greenwood             Senior Vice President--Corporate Development
</TABLE>
 
                                      A-40
<PAGE>
                                SCHEDULE 3.2(B)
                                       TO
                      AGREEMENT AND PLAN OF REORGANIZATION
 
            OFFICERS OF THE SURVIVING CORPORATION OF THE OSI MERGER
 
<TABLE>
<S>                            <C>
John K. Carlyle                Chairman
Donald J. Larson               President and Chief Executive Officer
John A. McCarthy               Executive Vice President--Managed Care Services
Richard A. Parr II             Executive Vice President, General Counsel, and Secretary
Joseph F. Pesce                Executive Vice President, Chief Financial Officer, and
                                 Treasurer
Daniel J. Thomas               Executive Vice President--Practice Management Services
W. Tom Fogarty, M.D.           Senior Vice President and Chief Medical Officer
Peter R. Gates                 Senior Vice President--Marketing and Sales
James M. Greenwood             Senior Vice President--Corporate Development
</TABLE>
 
                                      A-41
<PAGE>
                                SCHEDULE 3.2(C)
                                       TO
                      AGREEMENT AND PLAN OF REORGANIZATION
 
                         OFFICERS OF OCCUCENTERS, INC.
 
<TABLE>
<S>                            <C>
John K. Carlyle                Chairman
Donald J. Larson               President and Chief Executive Officer
Daniel J. Thomas               Executive Vice President--Practice Management Services
Richard A. Parr II             Executive Vice President, General Counsel, and Secretary
Joseph F. Pesce                Executive Vice President, Chief Financial Officer, and
                                 Treasurer
W. Tom Fogarty, M.D.           Senior Vice President and Chief Medical Officer
Peter R. Gates                 Senior Vice President--Marketing and Sales
James M. Greenwood             Senior Vice President--Corporate Development
</TABLE>
 
                                      A-42
<PAGE>
                                                                      APPENDIX B
 
                    OCCUSYSTEMS, INC. STOCK OPTION AGREEMENT
 
    OCCUSYSTEMS, INC. STOCK OPTION AGREEMENT (this "Agreement"), dated as of
April 21, 1997, by and between CRA Managed Care, Inc., a Massachusetts
corporation ("CRA"), and OccuSystems, Inc., a Delaware corporation ("OSI").
 
    WHEREAS, concurrently with the execution and delivery of this Agreement,
CRA, OSI and Concentra Managed Care, Inc., a Delaware corporation ("Holding
Company"), are entering into an Agreement and Plan of Reorganization, dated as
of the date hereof (the "Merger Agreement"), which provides that, among other
things, upon the terms and subject to the conditions thereof, OSI will be merged
with and into Holding Company (the "Merger"), with Holding Company continuing as
the surviving corporation;
 
    WHEREAS, as a condition to CRA's willingness to enter into the Merger
Agreement, CRA has requested that OSI agree, and OSI has so agreed, to grant to
CRA an option with respect to certain shares of OSI's common stock on the terms
and subject to the conditions set forth herein; and
 
    WHEREAS, concurrently with the execution and delivery of this Agreement, OSI
and CRA are entering into a CRA Stock Option Agreement (the "CRA Stock Option
Agreement") pursuant to which CRA has agreed to grant to OSI an option with
respect to certain shares of CRA's Common Stock on the terms and subject to the
conditions set forth therein.
 
    NOW, THEREFORE, in consideration of the foregoing and of the mutual
covenants and agreements set forth herein and in the Merger Agreement and for
other good and valuable consideration, the receipt and adequacy of which are
hereby acknowledged, the parties hereto agree as follows:
 
    1. GRANT OF OPTION.
 
        (a) OSI hereby grants CRA an irrevocable option (the "OSI Option") to
    purchase up to the Option Number (as hereinafter defined) of shares (the
    "OSI Shares") of common stock, par value $.01 per share, of OSI (the "OSI
    Common Stock"), in the manner set forth below at a price (the "Exercise
    Price") of $21.21 per OSI Share, payable in cash in accordance with Section
    4 hereof. As used herein, the "Option Number" shall initially be the number
    of shares equal to 10% of the total number of shares of OSI Common Stock
    issued and outstanding as of March 31, 1997, and shall be adjusted hereafter
    to reflect changes in OSI's capitalization occurring after the date hereof
    in accordance with Section 12. Capitalized terms used herein but not defined
    herein shall have the meanings set forth in the Merger Agreement.
 
        (b) Notwithstanding any other provision of this Agreement, in no event
    shall CRA's Total Profit (as hereinafter defined) exceed $15 million and, if
    it otherwise would exceed such amount, CRA, at its sole election, shall
    either (a) deliver to OSI for cancellation OSI Shares previously purchased
    by CRA, (b) pay cash to OSI or (c) undertake any combination thereof, so
    that CRA's Total Profit shall not exceed $15 million after taking into
    account the foregoing actions.
 
        (c) Notwithstanding any other provision of this Agreement, the OSI
    Option may not be exercised for a number of OSI Shares as would, as of the
    date of the Exercise Notice (as hereinafter defined), result in a Notional
    Total Profit (as hereinafter defined) of more than $15 million and, if
    exercise of the OSI Option otherwise would exceed such amount, CRA, at its
    discretion, may increase the Purchase Price for that number of OSI Shares
    set forth in the Exercise Notice so that the Notional Total Profit shall not
    exceed $15 million.
 
        (d) As used herein, the term "Total Profit" shall mean the aggregate
    amount (before taxes) of the following: (i) the amount of cash received by
    CRA pursuant to Section 9.5(a) of the Merger Agreement, (ii) (x) the amount
    received by CRA pursuant to OSI's repurchase of OSI Shares or the
 
                                      B-1
<PAGE>
    OSI Option pursuant to Section 7 hereof, less (y) CRA's purchase price for
    such OSI Shares, and (iii) (x) the net cash amounts received by CRA pursuant
    to the sale of OSI Shares (or any other securities into which such OSI
    Shares are converted or exchanged), less (y) CRA's purchase price for such
    OSI Shares.
 
        (e) As used herein, the term "Notional Total Profit" with respect to any
    number of OSI Shares as to which CRA may propose to exercise the OSI Option
    shall be the Total Profit determined as of the date of the Exercise Notice
    assuming that the OSI Option was exercised on such date for such number of
    OSI Shares and assuming that such OSI Shares, together with all other OSI
    Shares held by CRA and its affiliates as of such date, were sold for cash at
    the closing market price for the OSI Common Stock as of the close of
    business on the preceding trading day (less customary brokerage
    commissions).
 
    2. EXERCISE OF OPTION. The OSI Option may be exercised by CRA, in whole or
in part, at any time or from time to time after the occurrence of a "Trigger
Event". For purposes hereof, a "Trigger Event" shall mean an event that causes
OSI to pay the fee to CRA provided in Section 9.5(a) of the Merger Agreement. In
the event CRA wishes to exercise the OSI Option, CRA shall deliver to OSI a
written notice (an "Exercise Notice") specifying the total number of OSI Shares
it wishes to purchase. Each closing of a purchase of OSI Shares (a "Closing")
shall occur at a place, on a date and at a time designated by CRA in an Exercise
Notice delivered at least two business days prior to the date of the Closing.
The OSI Option shall terminate (the "Termination Date") upon the earlier of: (i)
the Effective Time; (ii) the termination of the Merger Agreement other than
under circumstances which also constitute a Trigger Event; or (iii) the 180th
day following a Trigger Event (or if, at the expiration of such period the OSI
Option cannot be exercised by reason of any applicable judgment, decree, order,
law or regulation, 10 business days after such impediment to exercise shall have
been removed or shall have become final and not subject to appeal but in no
event under this clause (iii) later than the 548th day following such Triggering
Event). Notwithstanding the foregoing, the OSI Option may not be exercised if
CRA is in material breach of any of its representations, warranties, covenants
or agreements contained in this Agreement or in the Merger Agreement.
 
    3. CONDITIONS TO CLOSING. The obligation of OSI to issue the OSI Shares to
CRA hereunder is subject to the conditions, which (other than the conditions
described in clauses (i) and (iii) below) may be waived by OSI in its sole
discretion, that (i) all waiting periods, if any, under the Hart-Scott-Rodino
Antitrust Improvements Act of 1976, as amended, and the rules and regulations
promulgated thereunder ("HSR Act"), applicable to the issuance of the OSI Shares
hereunder shall have expired or have been terminated, and all consents,
approvals, orders or authorizations of, or registrations, declarations or
filings with, any federal administrative agency or commission or other federal
governmental authority or instrumentality, if any, required in connection with
the issuance of the OSI Shares hereunder shall have been obtained or made, as
the case may be; (ii) the OSI Shares shall have been approved for quotation on
the Nasdaq Stock Market upon official notice of issuance; and (iii) no
preliminary or permanent injunction or other order by any court of competent
jurisdiction prohibiting or otherwise restraining such issuance shall be in
effect.
 
    4. CLOSING. At any Closing, (a) OSI will deliver to CRA a single certificate
in definitive form representing the number of OSI Shares designated by CRA in
its Exercise Notice, such certificate to be registered in the name of CRA and to
bear the legend set forth in Section 13, and (b) CRA will deliver to OSI the
aggregate price for the OSI Shares so designated and being purchased by wire
transfer of immediately available funds to a bank designated by OSI at the
Closing.
 
    5. REPRESENTATIONS AND WARRANTIES OF OSI. OSI represents and warrants to CRA
that (a) OSI is a corporation duly organized, validly existing and in good
standing under the laws of the State of Delaware and has the corporate power and
authority to enter into this Agreement and to carry out its obligations
hereunder, (b) the execution and delivery of this Agreement by OSI and the
consummation by OSI of the transactions contemplated hereby have been duly
authorized by all necessary corporate action on the part
 
                                      B-2
<PAGE>
of OSI and no other corporate proceedings on the part of OSI are necessary to
authorize this Agreement or any of the transactions contemplated hereby, (c)
this Agreement has been duly executed and delivered by OSI and constitutes a
valid and binding obligation of OSI, and, assuming this Agreement constitutes a
valid and binding obligation of CRA, is enforceable against OSI in accordance
with its terms, subject to applicable bankruptcy, insolvency, moratorium or
other similar laws relating to creditors' rights and general principles of
equity, (d) OSI has taken all necessary corporate action to authorize and
reserve for issuance and to permit it to issue, upon exercise of the OSI Option,
and at all times from the date hereof through the expiration of the OSI Option
will have reserved, a number of authorized and unissued OSI Shares not less than
the Option Number, all of which, upon their issuance and delivery in accordance
with the terms of this Agreement, will be validly issued, fully paid and
nonassessable, (e) upon delivery of OSI Shares to CRA upon the exercise of the
OSI Option, CRA will acquire OSI Shares, free and clear of all claims, liens,
charges, encumbrances and security interests of any nature whatsoever, (f) the
execution and delivery of this Agreement by OSI does not, and the performance of
this Agreement by OSI will not (i) violate the Certificate of Incorporation or
By-Laws of OSI, (ii) conflict with or violate any statute, rule, regulation,
order, judgment or decree applicable to OSI or by which it or any of its
property is bound or affected or (iii) result in any breach of or constitute a
default (or an event which with notice or lapse of time or both would become a
default) under, or give rise to any rights of termination, amendment,
acceleration or cancellation of, or result in the creation of a lien or
encumbrance on any of the property or assets of OSI pursuant to, any note, bond,
mortgage, indenture, contract, agreement, lease, license, or other instrument or
obligation to which OSI is a party or by which OSI or any of its property is
bound or affected, except, in the case of clauses (ii) and (iii) above, for
violations, breaches, defaults, rights, liens or encumbrances which would not,
individually or in the aggregate, have an OSI Material Adverse Effect, and (g)
the execution and delivery of this Agreement by OSI does not, and the
performance of this Agreement by OSI will not, require any consent, approval,
authorization or permit of, or filing with or notification to, any governmental
or regulatory authority except the pre-merger notification requirements of the
HSR Act.
 
    6. REPRESENTATIONS AND WARRANTIES OF CRA. CRA represents and warrants to OSI
that (a) CRA is a corporation duly organized, validly existing and in good
standing under the laws of the Commonwealth of Massachusetts and has the
corporate power and authority to enter into this Agreement and to carry out its
obligations hereunder, (b) the execution and delivery of this Agreement by CRA
and the consummation by CRA of the transactions contemplated hereby have been
duly authorized by all necessary corporate action on the part of CRA and no
other corporate proceedings on the part of CRA are necessary to authorize this
Agreement or any of the transactions contemplated hereby, (c) this Agreement has
been duly executed and delivered by CRA and constitutes a valid and binding
obligation of CRA, and, assuming this Agreement constitutes a valid and binding
obligation of OSI, is enforceable against CRA in accordance with its terms,
subject to applicable bankruptcy, insolvency, moratorium or other similar laws
relating to creditors' rights and general principles of equity, (d) the
execution and delivery of this Agreement by CRA does not, and the performance of
this Agreement by CRA will not (i) violate the Articles of Organization or
By-Laws of CRA, (ii) conflict with or violate any statute, rule, regulation,
order, judgment or decree applicable to CRA or by which it or any of its
property is bound or affected or (iii) result in any breach of or constitute a
default (or an event which with notice or lapse of time or both would become a
default) under, or give rise to any rights of termination, amendment,
acceleration or cancellation of, or result in the creation of a lien or
encumbrance on any of the property or assets of CRA pursuant to, any note, bond,
mortgage, indenture, contract, agreement, lease, license, or other instrument or
obligation to which CRA is a party or by which CRA or any of its property is
bound or affected, except, in the case of clauses (ii) and (iii) above, for
violations, breaches, defaults, rights, liens or encumbrances which would not,
individually or in the aggregate, have a CRA Material Adverse Effect, (e) the
execution and delivery of this Agreement by CRA does not, and the performance of
this Agreement by CRA will not, require any consent, approval, authorization or
permit of, or filing with or notification to, any governmental or regulatory
authority, except the pre-merger notification requirements of the HSR Act and
(f) any OSI Shares acquired upon
 
                                      B-3
<PAGE>
exercise of the OSI Option will not be, and the OSI Option is not being,
acquired by CRA with a view to the public distribution thereof.
 
    7. CERTAIN REPURCHASES.
 
        (a) CRA Put. At the request of CRA at any time during which the OSI
    Option would be exercisable pursuant to Section 2 (the "Repurchase Period"),
    OSI (or any successor entity thereof) shall, subject to the limitations set
    forth in Section 1, repurchase from CRA (1) the OSI Option, including any
    portion thereof, at the price set forth in subparagraph (i) below, or (2)
    OSI Shares purchased by CRA pursuant thereto, at a price set forth in
    subparagraph (ii) below:
 
            (i) the difference between the average of the closing sale prices of
       shares of OSI Common Stock on the Nasdaq Stock Market for the ten trading
       days immediately preceding the date CRA gives notice of its intent to
       exercise its rights under this Section 7 (the "Market Price") and the
       Exercise Price, multiplied by the number of the OSI Shares purchasable
       pursuant to the OSI Option (or portion thereof with respect to which CRA
       is exercising its rights under this Section 7), but only if the Market
       Price is greater than the Exercise Price; or
 
            (ii) the Exercise Price paid by CRA for the OSI Shares acquired
       pursuant to the OSI Option plus the difference between the Market Price
       and the Exercise Price, but only if the Market Price is greater than the
       Exercise Price, multiplied by the number of OSI Shares so purchased.
 
        (b) Payment and Redelivery of the OSI Option or Shares. In the event CRA
    exercises its rights under this Section 7, OSI shall, within 10 business
    days thereafter, pay the required amount to CRA by wire transfer of
    immediately available funds and CRA shall surrender to OSI the OSI Option or
    the certificates evidencing OSI Shares purchased by CRA pursuant thereto,
    and CRA shall warrant that it owns such shares and that such shares are then
    free and clear of all liens, claims, damages, charges and encumbrances of
    any kind or nature whatsoever.
 
    8. VOTING OF SHARES. Following the date hereof and prior to the Expiration
Date (as defined in Section 9(b)), each party shall vote any shares of capital
stock of the other party acquired by such party pursuant to this Agreement or
otherwise beneficially owned (within the meaning of Rule 13d-3 promulgated under
the Securities Exchange Act of 1934, as amended (the "Exchange Act")) by such
party (the shares so owned by a party collectively the "Restricted Shares") on
each matter submitted to a vote of stockholders of such other party for and
against such matter in the same proportion as the vote of all other stockholders
of such other party are voted (whether by proxy or otherwise) for and against
such matter.
 
    9. RESTRICTION ON CERTAIN ACTIONS.
 
        (a) Restrictions. Other than pursuant to the Merger Agreement, following
    the date hereof and prior to the Expiration Date, without the prior written
    consent of the other party, neither party shall, nor shall permit its
    affiliates to, directly or indirectly, alone or in concert or conjunction
    with any other Person or Group (as defined in Section 9(b)), (i) in any
    manner acquire, agree to acquire or make any proposal to acquire, any
    securities of, equity interest in, or any material property of, such other
    party or any of its subsidiaries (other than pursuant to this Agreement, the
    CRA Stock Option Agreement or the Merger Agreement), (ii) except at the
    specific written request of such other party, propose to enter into any
    merger or business combination involving such other party or any of its
    subsidiaries or to purchase a material portion of the assets of such other
    party or any of its subsidiaries, (iii) make or in any way participate in
    any "solicitation" of "proxies" (as such terms are used in Regulation 14A
    promulgated under the Exchange Act) to vote, or seek to advise or influence
    any Person with respect to the voting of, any voting securities of such
    other party or any of its subsidiaries, (iv) form, join or in any way
    participate in a Group with respect to any voting securities of such other
    party or any of its subsidiaries, (v) seek to control or influence the
    management, Board of Directors or policies of such other party, (vi)
    disclose any intention, plan or arrangement inconsistent with the foregoing,
 
                                      B-4
<PAGE>
    (vii) advise, assist or encourage any other Person in connection with the
    foregoing or (viii) request such other party (or its directors, officers,
    employees or agents), to amend or waive any provision of this Section 9, or
    take any action which may require such other party to make a public
    announcement regarding the possibility of a business combination or merger
    with such party.
 
        (b) Expiration Date. For purposes of this Agreement, (i) the term
    "Person" shall mean any corporation, partnership, individual, trust,
    unincorporated association or other entity or Group (within the meaning of
    Section 13(d)(3) of the Exchange Act), (ii) the term "Expiration Date" with
    respect to any obligation or restriction imposed on one party shall mean the
    earlier to occur of (A) the first anniversary of the date hereof and (B)
    such time as the other party shall have suffered a Change of Control and
    (iii) a "Change of Control" with respect to one party shall be deemed to
    have occurred whenever (A) there shall be consummated (1) any consolidation
    or merger of such party in which such party is not the continuing or
    surviving corporation, or pursuant to which shares of such party's common
    stock would be converted in whole or in part into cash, other securities or
    other property, other than a merger of such person in which the holders of
    such party's common stock immediately prior to the merger have substantially
    the same proportionate ownership of common stock of the surviving
    corporation immediately after the merger, or (2) any sale, lease, exchange
    or transfer (in one transaction or a series of related transactions) of all
    or substantially all the assets of such party, or (B) the stockholders of
    such party shall approve any plan or proposal for the liquidation or
    dissolution of such party, or (C) any party, other than such party or a
    subsidiary thereof or any employee benefit plan sponsored by such party or a
    subsidiary thereof or a corporation owned, directly or indirectly, by the
    stockholders of such party in substantially the same proportions as their
    ownership of stock of such party, shall become the beneficial owner of
    securities of such party representing 25% or more of the combined voting
    power of then outstanding securities ordinarily (and apart from rights
    accruing in special circumstances) having the right to vote in the election
    of directors, as a result of a tender or exchange offer, open market
    purchases, privately negotiated purchases or otherwise, or (D) at any time
    during the period commencing on the date of this Agreement and ending on the
    Expiration Date, individuals who at the date hereof constituted the Board of
    Directors of such party shall cease for any reason to constitute at least a
    majority thereof, unless the election or the nomination for election by such
    party's stockholders of each new director during the period commencing on
    the date of this Agreement and ending on the Expiration Date was approved by
    a vote of at least two-thirds of the directors then still in office who were
    directors at the date hereof, or (E) any other event shall occur with
    respect to such party that would be required to be reported in response to
    Item 6(e) (or any successor provision) of Schedule 14A of Regulation 14A
    promulgated under the Exchange Act.
 
    10. RESTRICTIONS ON TRANSFER.
 
        (a) Restrictions on Transfer. Prior to the Expiration Date, CRA shall
    not, directly or indirectly, by operation of law or otherwise, sell, assign,
    pledge or otherwise dispose of or transfer any Restricted Shares
    beneficially owned by it, other than (i) pursuant to Section 7, or (ii) in
    accordance with Section 10(b) or 11. Subsequent to the Expiration Date, CRA
    shall not, directly or indirectly, by operation of law or otherwise, sell,
    assign, pledge or otherwise dispose of or transfer any Restricted Shares
    beneficially owned by it to any purchaser, assignee, pledgee or other
    transferee who would, immediately after such sale, assignment, pledge,
    disposition or transfer, beneficially own more than 4.9% of the then
    outstanding voting power of the issuer of the Restricted Shares, except in
    accordance with Section 10(b) or Section 11.
 
        (b) Permitted Sales. Following the termination of the Merger Agreement,
    CRA shall be permitted to sell any Restricted Shares beneficially owned by
    it if such sale is made pursuant to a tender or exchange offer that has been
    approved or recommended, or otherwise determined to be fair and in the best
    interests of the stockholders of OSI, by a majority of the members of the
    Board of Directors of OSI (which majority shall include a majority of
    directors who were directors prior to the announcement of such tender or
    exchange offer).
 
                                      B-5
<PAGE>
    11. REGISTRATION RIGHTS. Following the termination of the Merger Agreement,
CRA (a "Designated Holder") may by written notice (the "Registration Notice") to
OSI (the "Registrant") request the Registrant to register under the Securities
Act all or any part of the Restricted Shares beneficially owned by such
Designated Holder (the "Registrable Securities") pursuant to a bonafide firm
commitment underwritten public offering in which the Designated Holder and the
underwriters shall effect as wide a distribution of such Registrable Securities
as is reasonably practicable and shall use their best efforts to prevent any
Person (including any Group) and its affiliates from purchasing through such
offering Restricted Shares representing more than 1% of the outstanding shares
of Common Stock of the Registrant on a fully diluted basis (a "Permitted
Offering"). The Registration Notice shall include a certificate executed by the
Designated Holder and its proposed managing underwriter, which underwriter shall
be an investment banking firm of nationally recognized standing and reasonably
satisfactory to the Registrant (the "Manager"), stating that (i) they have a
good faith intention to commence promptly a Permitted Offering and (ii) the
Manager in good faith believes that, based on the then prevailing market
conditions, it will be able to sell the Registrable Securities at a per share
price equal to at least 80% of the Fair Market Value of such shares. For
purposes hereof, the "Fair Market Value" of such shares shall mean the average
of the closing sales prices of such shares on the Nasdaq Stock Market (or such
other stock exchange or market system as shall then be the primary trading
market for such security) for the ten trading days immediately preceding the
Registration Notice. The Registrant (and/or any Person designated by the
Registrant) shall thereupon have the option exercisable by written notice
delivered to the Designated Holder within 10 business days after the receipt of
the Registration Notice, irrevocably to agree to purchase all or any part of the
Registrable Securities for cash at a price (the "Option Price") equal to the
product of (i) the number of Registrable Securities to be so purchased and (ii)
the Fair Market Value of such shares. Any such purchase of Registrable
Securities by the Registrant hereunder shall take place at a closing to be held
at the principal executive offices of the Registrant or its counsel at any
reasonable date and time designated by the Registrant and/or such designee in
such notice within 20 business days after delivery of such notice. Any payment
for the shares to be purchased shall be made by delivery at the time of such
closing of the Option Price in immediately available funds.
 
    If the Registrant does not elect to exercise its option pursuant to this
Section 11 with respect to all Registrable Securities, it shall use its
reasonable best efforts to effect, as promptly as practicable, the registration
under the Securities Act of the unpurchased Registrable Securities; provided,
however, that (i) neither party shall be entitled to more than an aggregate of
two effective registration statements hereunder and (ii) the Registrant will not
be required to file any such registration statement during any period of time
(not to exceed 40 days after such request in the case of clause (A) below or 90
days in the case of clauses (B) and (C) below) when (A) the Registrant is in
possession of material non-public information which it reasonably believes would
be detrimental to be disclosed at such time and, in the opinion of counsel to
such Registrant, such information would have to be disclosed if a registration
statement were filed at that time; (B) such Registrant is required under the
Securities Act to include audited financial statements for any period in such
registration statement and such financial statements are not yet available for
inclusion in such registration statement; or (C) such Registrant determines, in
its reasonable judgment, that such registration would interfere with any
financing, acquisition or other material transaction involving the Registrant or
any of its affiliates. If consummation of the sale of any Registrable Securities
pursuant to a registration hereunder does not occur within 90 days after the
filing with the Securities and Exchange Commission of the initial registration
statement, the provisions of this Section 11 shall again be applicable to any
proposed registration; provided, however, that neither party shall be entitled
to request more than two registrations pursuant to this Section 11. The
Registrant shall use its reasonable best efforts to cause any Registrable
Securities registered pursuant to this Section 11 to be qualified for sale under
the securities or Blue-Sky laws of such jurisdictions as the Designated Holder
may reasonably request and shall continue such registration or qualification in
effect in such jurisdiction; provided, however, that the Registrant shall not be
required to qualify to do business in, consent to general service of process in,
or subject itself to taxation in any jurisdiction by reason of this provision.
 
                                      B-6
<PAGE>
    The registration rights set forth in this Section 11 are subject to the
condition that the Designated Holder shall provide the Registrant with such
information with respect to such holder's Registrable Securities, the plans for
the distribution thereof, and such other information with respect to such holder
as, in the reasonable judgment of counsel for the Registrant, is necessary to
enable the Registrant to include in such registration statement all material
facts required to be disclosed with respect to a registration thereunder.
 
    A registration effected under this Section 11 shall be effected at the
Registrant's expense, except for underwriting discounts and commissions and the
fees and expenses of counsel to the Holder, and the Registrant shall provide to
the underwriters such documentation (including certificates, opinions of counsel
and "comfort" letters from auditors) as are customary in connection with
underwritten public offerings as such underwriters may reasonably require. In
connection with any such registration, the parties agree (i) to indemnify each
other and the underwriters in the customary manner and (ii) to enter into an
underwriting agreement in form and substance customary to transactions of this
type with the Manager and the other underwriters participating in such offering.
 
    12. ADJUSTMENT UPON CHANGES IN CAPITALIZATION. In the event of any change in
OSI Common Stock by reason of stock dividends, splitups, mergers (other than the
Merger), recapitalizations, combinations, exchange of shares or the like, the
type and number of shares or securities subject to the OSI Option, and the
purchase price per share provided in Section 1, shall be adjusted appropriately.
 
    13. RESTRICTIVE LEGENDS. Each certificate representing shares of OSI Common
Stock issued to CRA hereunder, shall include a legend in substantially the
following form:
 
    THE SECURITIES REPRESENTED BY THIS CERTIFICATE HAVE NOT BEEN REGISTERED
UNDER THE SECURITIES ACT OF 1933, AS AMENDED, AND MAY BE REOFFERED OR SOLD ONLY
IF SO REGISTERED OR IF AN EXEMPTION FROM SUCH REGISTRATION IS AVAILABLE. SUCH
SECURITIES ARE ALSO SUBJECT TO ADDITIONAL RESTRICTIONS ON TRANSFER AS SET FORTH
IN THE STOCK OPTION AGREEMENT, DATED AS OF APRIL 21, 1997, A COPY OF WHICH MAY
BE OBTAINED FROM OCCUSYSTEMS, INC.
 
    14. BINDING EFFECT; NO ASSIGNMENT. This Agreement shall be binding upon and
inure to the benefit of the parties hereto and their respective successors and
permitted assigns. Except as expressly provided for in this Agreement, neither
this Agreement nor the rights or the obligations of either party hereto are
assignable, except by operation of law, or with the written consent of the other
party. Nothing contained in this Agreement, express or implied, is intended to
confer upon any person other than the parties hereto and their respective
permitted assigns any rights or remedies of any nature whatsoever by reason of
this Agreement. Any Restricted Shares sold by a party in compliance with the
provisions of Section 10 or 11 shall, upon consummation of such sale, be free of
the restrictions imposed with respect to such shares by this Agreement, unless
and until such party shall repurchase or otherwise become the beneficial owner
of such shares, and any transferee of such shares shall not be entitled to the
rights of such party. Certificates representing shares sold in a registered
public offering pursuant to Section 11 shall not be required to bear the legend
set forth in Section 13.
 
    15. SPECIFIC PERFORMANCE. The parties recognize and agree that if for any
reason any of the provisions of this Agreement are not performed in accordance
with their specific terms or are otherwise breached, immediate and irreparable
harm or injury would be caused for which money damages would not be an adequate
remedy. Accordingly, each party agrees that, in addition to other remedies, the
other party shall be entitled to an injunction restraining any violation or
threatened violation of the provisions of this Agreement. In the event that any
action should be brought in equity to enforce the provisions of the Agreement,
neither party will allege, and each party hereby waives the defense, that there
is adequate remedy at law.
 
                                      B-7
<PAGE>
    16. ENTIRE AGREEMENT. This Agreement, the Confidentiality Agreement dated
March 19, 1997 between OSI and CRA (other than "standstill" provisions thereof,
which are superseded pursuant ot Section 10.4 of the Management Agreement), the
Merger Agreement (including the exhibits and schedules thereto) and the CRA
Stock Option Agreement constitute the entire agreement among the parties with
respect to the subject matter hereof and supersede all other prior agreements
and understandings, both written and oral, among the parties or any of them with
respect to the subject matter hereof.
 
    17. FURTHER ASSURANCES. Each party will execute and deliver all such further
documents and instruments and take all such further action as may be necessary
in order to consummate the transactions contemplated hereby.
 
    18. VALIDITY. The invalidity or unenforceability of any provision of this
Agreement shall not affect the validity or enforceability of the other
provisions of this Agreement, which shall remain in full force and effect. In
the event any court or other competent authority holds any provision of this
Agreement to be null, void or unenforceable, the parties hereto shall negotiate
in good faith the execution and delivery of an amendment to this Agreement in
order, as nearly as possible, to effectuate, to the extent permitted by law, the
intent of the parties hereto with respect to such provision. Each party agrees
that, should any court or other competent authority hold any provision of this
Agreement or part hereof to be null, void or unenforceable, or order any party
to take any action inconsistent herewith, or not take any action required
herein, the other party shall not be entitled to specific performance of such
provision or part hereof or to any other remedy, including but not limited to
money damages, for breach hereof or of any other provision of this Agreement or
part hereof as the result of such holding or order.
 
    19. NOTICES. Any notice or communication required or permitted hereunder
shall be in writing and either delivered personally, telegraphed or telecopied
or sent by next day delivery by a nationally recognized overnight delivery
service or by certified or registered mail, postage prepaid, and shall be deemed
to be given, dated and received (i) when so delivered personally, (ii) upon
receipt of an appropriate electronic answerback or confirmation when so
delivered by telegraph or telecopy (to such number specified below or another
number or numbers as such person may subsequently designate by notice hereunder)
or (iii) one business day after sending by overnight delivery, and five business
days after the date of mailing by certified or registered mail, to the following
address or to such other address or addresses as such person may subsequently
designate by notice given hereunder, if so delivered by mail:
 
If to CRA:
 
CRA Managed Care, Inc.
312 Union Wharf
Boston, Massachusetts 02109
Attention: Chairman
Telecopier No.: (617) 720-1259
 
                                      B-8
<PAGE>
With copies to:
 
Hutchins, Wheeler & Dittmar
A Professional Corporation
101 Federal Street
Boston, MA 02110
Attention: James Westra, Esq.
Telecopier No.: (617) 951-1295
 
If to OSI:
 
OccuSystems, Inc.
3010 LBJ Freeway
Suite 400
Dallas, Texas 75234
Attention: General Counsel
Telecopier No.: (972) 243-7540
 
With copies to:
 
Vinson & Elkins LLP
2001 Ross Avenue
Suite 3700
Dallas TX 75201
Attention: Jeffrey A. Chapman
Telecopier No.: (214) 220-7716
 
    20. GOVERNING LAW. This Agreement shall be governed by and construed in
accordance with the laws of the State of Delaware applicable to agreements made
and to be performed entirely within such State.
 
    21. DESCRIPTIVE HEADINGS. The descriptive headings herein are inserted for
convenience of reference only and are not intended to be part of or to affect
the meaning or interpretation of this Agreement.
 
    22. COUNTERPARTS. This Agreement may be executed in two counterparts, each
of which shall be deemed to be an original, but both of which, taken together,
shall constitute one and the same instrument.
 
    23. EXPENSES. Except as otherwise expressly provided herein or in the Merger
Agreement, all costs and expenses incurred in connection with the transactions
contemplated by this Agreement shall be paid by the party incurring such
expenses.
 
    24. AMENDMENTS; WAIVER. This Agreement may be amended by the parties hereto
and the terms and conditions hereof may be waived only by an instrument in
writing signed on behalf of each of the parties hereto, or, in the case of a
waiver, by an instrument signed on behalf of the party waiving compliance.
 
    IN WITNESS WHEREOF, the parties hereto have caused this Agreement to be
executed by their respective duly authorized officers as of the date first above
written.
 
                                        CRA MANAGED CARE, INC.
 
                                        By: /S/ DONALD J. LARSON
                                          --------------------------------------
 
                                            Title: PRESIDENT & CHIEF EXECUTIVE
                                                          OFFICER
 
                                        OCCUSYSTEMS, INC.
 
                                        By: /s/ JOHN K. CARLYLE
                                          --------------------------------------
 
                                            Title: CHAIRMAN & CHIEF EXECUTIVE
                                                          OFFICER
 
                                      B-9
<PAGE>
                                                                      APPENDIX C
 
                 CRA MANAGED CARE, INC. STOCK OPTION AGREEMENT
 
    CRA MANAGED CARE, INC. STOCK OPTION AGREEMENT (this "Agreement"), dated as
of April 21, 1997 by and between OccuSystems, Inc., a Delaware corporation
("OSI"), and CRA Managed Care, Inc., a Massachusetts corporation ("CRA").
 
    WHEREAS, concurrently with the execution and delivery of this Agreement,
OSI, CRA and Concentra Managed Care, Inc. a Delaware corporation ("Holding
Company"), are entering into an Agreement and Plan of Reorganization, dated as
of the date hereof (the "Merger Agreement"), which provides that, among other
things, upon the terms and subject to the conditions thereof, CRA will be merged
with a wholly owned subsidiary of Holding Company (the "Merger"), with CRA
continuing as the surviving corporation;
 
    WHEREAS, as a condition to OSI's willingness to enter into the Merger
Agreement, OSI has requested that CRA agree, and CRA has so agreed, to grant to
OSI an option with respect to certain shares of CRA's common stock on the terms
and subject to the conditions set forth herein; and
 
    WHEREAS, concurrently with the execution and delivery of this Agreement, CRA
and OSI are entering into an OSI Stock Option Agreement (the "OSI Stock Option
Agreement") pursuant to which OSI has agreed to grant to CRA an option with
respect to certain shares of OSI's Common Stock on the terms and subject to the
conditions set forth therein.
 
    NOW, THEREFORE, in consideration of the foregoing and of the mutual
covenants and agreements set forth herein and in the Merger Agreement and for
other good and valuable consideration, the receipt and adequacy of which are
hereby acknowledged, the parties hereto agree as follows:
 
    1. GRANT OF OPTION.
 
    (a) CRA hereby grants OSI an irrevocable option (the "CRA Option") to
purchase up to the Option Number (as hereinafter defined) of shares (the "CRA
Shares") of common stock, par value $.01 per share, of CRA (the "CRA Common
Stock"), in the manner set forth below at a price (the "Exercise Price") of $37
7/8 per CRA Share, payable in cash in accordance with Section 4 hereof. As used
herein, the "Option Number" shall initially be the number of shares equal to 10%
of the total number of shares of CRA Common Stock issued and outstanding as of
March 31, 1997, and shall be adjusted hereafter to reflect changes in CRA's
capitalization occurring after the date hereof in accordance with Section 12.
Capitalized terms used herein but not defined herein shall have the meanings set
forth in the Merger Agreement.
 
    (b) Notwithstanding any other provision of this Agreement, in no event shall
OSI's Total Profit (as hereinafter defined) exceed $15 million and, if it
otherwise would exceed such amount, OSI, at its sole election, shall either (a)
deliver to CRA for cancellation CRA Shares previously purchased by OSI, (b) pay
cash to CRA or (c) undertake any combination thereof, so that OSI's Total Profit
shall not exceed $15 million after taking into account the foregoing actions.
 
    (c) Notwithstanding any other provision of this Agreement, the CRA Option
may not be exercised for a number of CRA Shares as would, as of the date of the
Exercise Notice (as hereinafter defined), result in a Notional Total Profit (as
hereinafter defined) of more than $15 million and, if exercise of the CRA Option
otherwise would exceed such amount, OSI, at its discretion, may increase the
Purchase Price for that number of CRA Shares set forth in the Exercise Notice so
that the Notional Total Profit shall not exceed $15 million.
 
    (d) As used herein, the term "Total Profit" shall mean the aggregate amount
(before taxes) of the following: (i) the amount of cash received by OSI pursuant
to Section 9.5(b) of the Merger Agreement, (ii)
 
                                      C-1
<PAGE>
(x) the amount received by OSI pursuant to CRA's repurchase of CRA Shares or the
CRA Option pursuant to Section 7 hereof, less (y) OSI's purchase price for such
CRA Shares, and (iii) (x) the net cash amounts received by OSI pursuant to the
sale of CRA Shares (or any other securities into which such CRA Shares are
converted or exchanged), less (y) OSI's purchase price for such CRA Shares.
 
    (e) As used herein, the term "Notional Total Profit" with respect to any
number of CRA Shares as to which OSI may propose to exercise the CRA Option
shall be the Total Profit determined as of the date of the Exercise Notice
assuming that the CRA Option was exercised on such date for such number of CRA
Shares and assuming that such CRA Shares, together with all other CRA Shares
held by OSI and its affiliates as of such date, were sold for cash at the
closing market price for the CRA Common Stock as of the close of business on the
preceding trading day (less customary brokerage commissions).
 
    2. EXERCISE OF OPTION. The CRA Option may be exercised by OSI, in whole or
in part, at any time or from time to time after the occurrence of a "Trigger
Event". For purposes hereof, a "Trigger Event" shall mean an event that causes
CRA to pay the fee to OSI provided in Section 9.5(b) of the Merger Agreement. In
the event OSI wishes to exercise the CRA Option, OSI shall deliver to CRA a
written notice (an "Exercise Notice") specifying the total number of CRA Shares
it wishes to purchase. Each closing of a purchase of CRA Shares (a "Closing")
shall occur at a place, on a date and at a time designated by OSI in an Exercise
Notice delivered at least two business days prior to the date of the Closing.
The CRA Option shall terminate (the "Termination Date") upon the earlier of: (i)
the Effective Time; (ii) the termination of the Merger Agreement other than
under circumstances which also constitute a Trigger Event; or (iii) the 180th
day following a Trigger Event (or if, at the expiration of such period the CRA
Option cannot be exercised by reason of any applicable judgment, decree, order,
law or regulation, 10 business days after such impediment to exercise shall have
been removed or shall have become final and not subject to appeal but in no
event under this clause (iii) later than the 548th day following such Triggering
Event). Notwithstanding the foregoing, the CRA Option may not be exercised if
OSI is in material breach of any of its representations, warranties, covenants
or agreements contained in this Agreement or in the Merger Agreement.
 
    3. CONDITIONS TO CLOSING. The obligation of CRA to issue the CRA Shares to
OSI hereunder is subject to the conditions, which (other than the conditions
described in clauses (i) and (iii) below) may be waived by CRA in its sole
discretion, that (i) all waiting periods, if any, under the Hart-Scott-Rodino
Antitrust Improvements Act of 1976, as amended, and the rules and regulations
promulgated thereunder ("HSR Act"), applicable to the issuance of the CRA Shares
hereunder shall have expired or have been terminated, and all consents,
approvals, orders or authorizations of, or registrations, declarations or
filings with, any federal administrative agency or commission or other federal
governmental authority or instrumentality, if any, required in connection with
the issuance of the CRA Shares hereunder shall have been obtained or made, as
the case may be; (ii) the CRA Shares shall have been approved for quotation on
the Nasdaq Stock Market upon official notice of issuance; and (iii) no
preliminary or permanent injunction or other order by any court of competent
jurisdiction prohibiting or otherwise restraining such issuance shall be in
effect.
 
    4. CLOSING. At any Closing, (a) CRA will deliver to OSI a single certificate
in definitive form representing the number of CRA Shares designated by OSI in
its Exercise Notice, such certificate to be registered in the name of OSI and to
bear the legend set forth in Section 13, and (b) OSI will deliver to CRA the
aggregate price for the CRA Shares so designated and being purchased by wire
transfer of immediately available funds to a bank designated by CRA at the
Closing.
 
    5. REPRESENTATIONS AND WARRANTIES OF CRA. CRA represents and warrants to OSI
that (a) CRA is a corporation duly organized, validly existing and in good
standing under the laws of the Commonwealth of Massachusetts and has the
corporate power and authority to enter into this Agreement and to carry out its
obligations hereunder, (b) the execution and delivery of this Agreement by CRA
and the consummation by CRA of the transactions contemplated hereby have been
duly authorized by all necessary corporate action
 
                                      C-2
<PAGE>
on the part of CRA and no other corporate proceedings on the part of CRA are
necessary to authorize this Agreement or any of the transactions contemplated
hereby, (d) this Agreement has been duly executed and delivered by CRA and
constitutes a valid and binding obligation of CRA, and, assuming this Agreement
constitutes a valid and binding obligation of OSI, is enforceable against CRA in
accordance with its terms, subject to applicable bankruptcy, insolvency,
moratorium or other similar laws relating to creditors' rights and general
principles of equity, (d) CRA has taken all necessary corporate action to
authorize and reserve for issuance and to permit it to issue, upon exercise of
the CRA Option, and at all times from the date hereof through the expiration of
the CRA Option will have reserved, a number of authorized and unissued CRA
Shares not less than the Option Number, all of which, upon their issuance and
delivery in accordance with the terms of this Agreement, will be validly issued,
fully paid and nonassessable, (e) upon delivery of CRA Shares to OSI upon the
exercise of the CRA Option, OSI will acquire CRA Shares, free and clear of all
claims, liens, charges, encumbrances and security interests of any nature
whatsoever, (f) the execution and delivery of this Agreement by CRA does not,
and the performance of this Agreement by CRA will not (i) violate the Articles
of Organization or By-Laws of CRA, (ii) conflict with or violate any statute,
rule, regulation, order, judgment or decree applicable to CRA or by which it or
any of its property is bound or affected or (iii) result in any breach of or
constitute a default (or an event which with notice or lapse of time or both
would become a default) under, or give rise to any rights of termination,
amendment, acceleration or cancellation of, or result in the creation of a lien
or encumbrance on any of the property or assets of CRA pursuant to, any note,
bond, mortgage, indenture, contract, agreement, lease, license, or other
instrument or obligation to which CRA is a party or by which CRA or any of its
property is bound or affected, except, in the case of clauses (ii) and (iii)
above, for violations, breaches, defaults, rights, liens or encumbrances which
would not, individually or in the aggregate, have a CRA Material Adverse Effect,
and (g) the execution and delivery of this Agreement by CRA does not, and the
performance of this Agreement by CRA will not, require any consent, approval,
authorization or permit of, or filing with or notification to, any governmental
or regulatory authority except the pre-merger notification requirements of the
HSR Act.
 
    6. REPRESENTATIONS AND WARRANTIES OF OSI. OSI represents and warrants to CRA
that (a) OSI is a corporation duly organized, validly existing and in good
standing under the laws of the State of Delaware and has the corporate power and
authority to enter into this Agreement and to carry out its obligations
hereunder, (b) the execution and delivery of this Agreement by OSI and the
consummation by OSI of the transactions contemplated hereby have been duly
authorized by all necessary corporate action on the part of OSI and no other
corporate proceedings on the part of OSI are necessary to authorize this
Agreement or any of the transactions contemplated hereby, (c) this Agreement has
been duly executed and delivered by OSI and constitutes a valid and binding
obligation of OSI, and, assuming this Agreement constitutes a valid and binding
obligation of CRA, is enforceable against OSI in accordance with its terms,
subject to applicable bankruptcy, insolvency, moratorium or other similar laws
relating to creditors' rights and general principles of equity, (d) the
execution and delivery of this Agreement by OSI does not, and the performance of
this Agreement by OSI will not (i) violate the Certificate of Incorporation or
By-Laws of OSI, (ii) conflict with or violate any statute, rule, regulation,
order, judgment or decree applicable to OSI or by which it or any of its
property is bound or affected or (iii) result in any breach of or constitute a
default (or an event which with notice or lapse of time or both would become a
default) under, or give rise to any rights of termination, amendment,
acceleration or cancellation of, or result in the creation of a lien or
encumbrance on any of the property or assets of OSI pursuant to, any note, bond,
mortgage, indenture, contract, agreement, lease, license, or other instrument or
obligation to which OSI is a party or by which OSI or any of its property is
bound or affected, except, in the case of clauses (ii) and (iii) above, for
violations, breaches, defaults, rights, liens or encumbrances which would not,
individually or in the aggregate, have an OSI Material Adverse Effect, (e) the
execution and delivery of this Agreement by OSI does not, and the performance of
this Agreement by OSI will not, require any consent, approval, authorization or
permit of, or filing with or notification to, any governmental or regulatory
authority, except the pre-merger notification requirements of the HSR Act and
(f) any CRA Shares acquired upon
 
                                      C-3
<PAGE>
exercise of the CRA Option will not be, and the CRA Option is not being,
acquired by OSI with a view to the public distribution thereof.
 
    7. CERTAIN REPURCHASES.
 
    (a) OSI PUT. At the request of OSI at any time during which the CRA Option
would be exercisable pursuant to Section 2 (the "Repurchase Period"), CRA (or
any successor entity thereof) shall, subject to the limitations set forth in
Section 1, repurchase from OSI (1) the CRA Option, including any portion
thereof, at the price set forth in subparagraph (i) below, or (2) CRA Shares
purchased by OSI pursuant thereto, at a price set forth in subparagraph (ii)
below:
 
        (i) the difference between the average of the closing sale prices of
    shares of CRA Common Stock on the Nasdaq Stock Market for the ten trading
    days immediately preceding the date OSI gives notice of its intent to
    exercise its rights under this Section 7 (the "Market Price") and the
    Exercise Price, multiplied by the number of the CRA Shares purchasable
    pursuant to the CRA Option (or portion thereof with respect to which OSI is
    exercising its rights under this Section 7), but only if the Market Price is
    greater than the Exercise Price; or
 
        (ii) the Exercise Price paid by OSI for the CRA Shares acquired pursuant
    to the CRA Option plus the difference between the Market Price and the
    Exercise Price, but only if the Market Price is greater than the Exercise
    Price, multiplied by the number of CRA Shares so purchased.
 
    (b) PAYMENT AND REDELIVERY OF THE CRA OPTION OR SHARES. In the event OSI
exercises its rights under this Section 7, CRA shall, within 10 business days
thereafter, pay the required amount to OSI by wire transfer of immediately
available funds and OSI shall surrender to CRA the CRA Option or the
certificates evidencing CRA Shares purchased by OSI pursuant thereto, and OSI
shall warrant that it owns such shares and that such shares are then free and
clear of all liens, claims, damages, charges and encumbrances of any kind or
nature whatsoever.
 
    8. VOTING OF SHARES. Following the date hereof and prior to the Expiration
Date (as defined in Section 9(b)), each party shall vote any shares of capital
stock of the other party acquired by such party pursuant to this Agreement or
otherwise beneficially owned (within the meaning of Rule 13d-3 promulgated under
the Securities Exchange Act of 1934, as amended (the "Exchange Act")) by such
party (the shares so owned by a party collectively the "Restricted Shares") on
each matter submitted to a vote of stockholders of such other party for and
against such matter in the same proportion as the vote of all other stockholders
of such other party are voted (whether by proxy or otherwise) for and against
such matter.
 
    9. RESTRICTION ON CERTAIN ACTIONS.
 
    (a) RESTRICTIONS. Other than pursuant to the Merger Agreement, following the
date hereof and prior to the Expiration Date, without the prior written consent
of the other party, neither party shall, nor shall permit its affiliates to,
directly or indirectly, alone or in concert or conjunction with any other Person
or Group (as defined in Section 9(b)), (i) in any manner acquire, agree to
acquire or make any proposal to acquire, any securities of, equity interest in,
or any material property of, such other party or any of its subsidiaries (other
than pursuant to this Agreement, the OSI Stock Option Agreement or the Merger
Agreement), (ii) except at the specific written request of such other party,
propose to enter into any merger or business combination involving such other
party or any of its subsidiaries or to purchase a material portion of the assets
of such other party or any of its subsidiaries, (iii) make or in any way
participate in any "solicitation" of "proxies" (as such terms are used in
Regulation 14A promulgated under the Exchange Act) to vote, or seek to advise or
influence any Person with respect to the voting of, any voting securities of
such other party or any of its subsidiaries, (iv) form, join or in any way
participate in a Group with respect to any voting securities of such other party
or any of its subsidiaries, (v) seek to control or influence the management,
Board of Directors or policies of such other party, (vi) disclose any intention,
plan or arrangement inconsistent with the foregoing, (vii) advise, assist or
encourage any other Person in connection with the foregoing or (viii) request
such other party (or its directors, officers,
 
                                      C-4
<PAGE>
employees or agents), to amend or waive any provision of this Section 9, or take
any action which may require such other party to make a public announcement
regarding the possibility of a business combination or merger with such party.
 
    (b) EXPIRATION DATE. For purposes of this Agreement, (i) the term "Person"
shall mean any corporation, partnership, individual, trust, unincorporated
association or other entity or Group (within the meaning of Section 13(d)(3) of
the Exchange Act), (ii) the term "Expiration Date" with respect to any
obligation or restriction imposed on one party shall mean the earlier to occur
of (A) the first anniversary of the date hereof and (B) such time as the other
party shall have suffered a Change of Control and (iii) a "Change of Control"
with respect to one party shall be deemed to have occurred whenever (A) there
shall be consummated (1) any consolidation or merger of such party in which such
party is not the continuing or surviving corporation, or pursuant to which
shares of such party's common stock would be converted in whole or in part into
cash, other securities or other property, other than a merger of such person in
which the holders of such party's common stock immediately prior to the merger
have substantially the same proportionate ownership of common stock of the
surviving corporation immediately after the merger, or (2) any sale, lease,
exchange or transfer (in one transaction or a series of related transactions) of
all or substantially all the assets of such party, or (B) the stockholders of
such party shall approve any plan or proposal for the liquidation or dissolution
of such party, or (C) any party, other than such party or a subsidiary thereof
or any employee benefit plan sponsored by such party or a subsidiary thereof or
a corporation owned, directly or indirectly, by the stockholders of such party
in substantially the same proportions as their ownership of stock of such party,
shall become the beneficial owner of securities of such party representing 25%
or more of the combined voting power of then outstanding securities ordinarily
(and apart from rights accruing in special circumstances) having the right to
vote in the election of directors, as a result of a tender or exchange offer,
open market purchases, privately negotiated purchases or otherwise, or (D) at
any time during the period commencing on the date of this Agreement and ending
on the Expiration Date, individuals who at the date hereof constituted the Board
of Directors of such party shall cease for any reason to constitute at least a
majority thereof, unless the election or the nomination for election by such
party's stockholders of each new director during the period commencing on the
date of this Agreement and ending on the Expiration Date was approved by a vote
of at least two-thirds of the directors then still in office who were directors
at the date hereof, or (E) any other event shall occur with respect to such
party that would be required to be reported in response to Item 6(e) (or any
successor provision) of Schedule 14A of Regulation 14A promulgated under the
Exchange Act.
 
    10. RESTRICTIONS ON TRANSFER.
 
    (a) RESTRICTIONS ON TRANSFER. Prior to the Expiration Date, OSI shall not,
directly or indirectly, by operation of law or otherwise, sell, assign, pledge
or otherwise dispose of or transfer any Restricted Shares beneficially owned by
it, other than (i) pursuant to Section 7, or (ii) in accordance with Section
10(b) or 11. Subsequent to the Expiration Date, OSI shall not, directly or
indirectly, by operation of law or otherwise, sell, assign, pledge or otherwise
dispose of or transfer any Restricted Shares beneficially owned by it to any
purchaser, assignee, pledgee or other transferee who would, immediately after
such sale, assignment, pledge, disposition or transfer, beneficially own more
than 4.9% of the then outstanding voting power of the issuer of the Restricted
Shares, except in accordance with Section 10(b) or Section 11.
 
    (b) PERMITTED SALES. Following the termination of the Merger Agreement, OSI
shall be permitted to sell any Restricted Shares beneficially owned by it if
such sale is made pursuant to a tender or exchange offer that has been approved
or recommended, or otherwise determined to be fair and in the best interests of
the stockholders of CRA, by a majority of the members of the Board of Directors
of CRA (which majority shall include a majority of directors who were directors
prior to the announcement of such tender or exchange offer).
 
    11. REGISTRATION RIGHTS. Following the termination of the Merger Agreement,
OSI (a "Designated Holder") may by written notice (the "Registration Notice") to
CRA (the "Registrant") request the
 
                                      C-5
<PAGE>
Registrant to register under the Securities Act all or any part of the
Restricted Shares beneficially owned by such Designated Holder (the "Registrable
Securities") pursuant to a bonafide firm commitment underwritten public offering
in which the Designated Holder and the underwriters shall effect as wide a
distribution of such Registrable Securities as is reasonably practicable and
shall use their best efforts to prevent any Person (including any Group) and its
affiliates from purchasing through such offering Restricted Shares representing
more than 1% of the outstanding shares of Common Stock of the Registrant on a
fully diluted basis (a "Permitted Offering"). The Registration Notice shall
include a certificate executed by the Designated Holder and its proposed
managing underwriter, which underwriter shall be an investment banking firm of
nationally recognized standing and reasonably satisfactory to the Registrant
(the "Manager"), stating that (i) they have a good faith intention to commence
promptly a Permitted Offering and (ii) the Manager in good faith believes that,
based on the then prevailing market conditions, it will be able to sell the
Registrable Securities at a per share price equal to at least 80% of the Fair
Market Value of such shares. For purposes hereof, the "Fair Market Value" of
such shares shall mean the average of the closing sales prices of such shares on
the Nasdaq Stock Market (or such other stock exchange or market system as shall
then be the primary trading market for such security) for the ten trading days
immediately preceding the Registration Notice. The Registrant (and/or any Person
designated by the Registrant) shall thereupon have the option exercisable by
written notice delivered to the Designated Holder within 10 business days after
the receipt of the Registration Notice, irrevocably to agree to purchase all or
any part of the Registrable Securities for cash at a price (the "Option Price")
equal to the product of (i) the number of Registrable Securities to be purchased
and (ii) the Fair Market Value of such shares. Any such purchase of Registrable
Securities by the Registrant hereunder shall take place at a closing to be held
at the principal executive offices of the Registrant or its counsel at any
reasonable date and time designated by the Registrant and/or such designee in
such notice within 20 business days after delivery of such notice. Any payment
for the shares to be purchased shall be made by delivery at the time of such
closing of the Option Price in immediately available funds.
 
    If the Registrant does not elect to exercise its option pursuant to this
Section 11 with respect to all Registrable Securities, it shall use its
reasonable best efforts to effect, as promptly as practicable, the registration
under the Securities Act of the unpurchased Registrable Securities; provided,
however, that (i) neither party shall be entitled to more than an aggregate of
two effective registration statements hereunder and (ii) the Registrant will not
be required to file any such registration statement during any period of time
(not to exceed 40 days after such request in the case of clause (A) below or 90
days in the case of clauses (B) and (C) below) when (A) the Registrant is in
possession of material non-public information which it reasonably believes would
be detrimental to be disclosed at such time and, in the opinion of counsel to
such Registrant, such information would have to be disclosed if a registration
statement were filed at that time; (B) such Registrant is required under the
Securities Act to include audited financial statements for any period in such
registration statement and such financial statements are not yet available for
inclusion in such registration statement; or (C) such Registrant determines, in
its reasonable judgment, that such registration would interfere with any
financing, acquisition or other material transaction involving the Registrant or
any of its affiliates. If consummation of the sale of any Registrable Securities
pursuant to a registration hereunder does not occur within 90 days after the
filing with the Securities and Exchange Commission of the initial registration
statement, the provisions of this Section 11 shall again be applicable to any
proposed registration; provided, however, that neither party shall be entitled
to request more than two registrations pursuant to this Section 11. The
Registrant shall use its reasonable best efforts to cause any Registrable
Securities registered pursuant to this Section 11 to be qualified for sale under
the securities or Blue-Sky laws of such jurisdictions as the Designated Holder
may reasonably request and shall continue such registration or qualification in
effect in such jurisdiction; provided, however, that the Registrant shall not be
required to qualify to do business in, consent to general service of process in,
or subject itself to taxation in any jurisdiction by reason of this provision.
 
    The registration rights set forth in this Section 11 are subject to the
condition that the Designated Holder shall provide the Registrant with such
information with respect to such holder's Registrable
 
                                      C-6
<PAGE>
Securities, the plans for the distribution thereof, and such other information
with respect to such holder as, in the reasonable judgment of counsel for the
Registrant, is necessary to enable the Registrant to include in such
registration statement all material facts required to be disclosed with respect
to a registration thereunder.
 
    A registration effected under this Section 11 shall be effected at the
Registrant's expense, except for underwriting discounts and commissions and the
fees and expenses of counsel to the Holder, and the Registrant shall provide to
the underwriters such documentation (including certificates, opinions of counsel
and "comfort" letters from auditors) as are customary in connection with
underwritten public offerings as such underwriters may reasonably require. In
connection with any such registration, the parties agree (i) to indemnify each
other and the underwriters in the customary manner and (ii) to enter into an
underwriting agreement in form and substance customary to transactions of this
type with the Manager and the other underwriters participating in such offering.
 
    12. ADJUSTMENT UPON CHANGES IN CAPITALIZATION. In the event of any change in
CRA Common Stock by reason of stock dividends, splitups, mergers (other than the
Merger), recapitalizations, combinations, exchange of shares or the like, the
type and number of shares or securities subject to the CRA Option, and the
purchase price per share provided in Section 1, shall be adjusted appropriately.
 
    13. RESTRICTIVE LEGENDS. Each certificate representing shares of CRA Common
Stock issued to OSI hereunder, shall include a legend in substantially the
following form:
 
    THE SECURITIES REPRESENTED BY THIS CERTIFICATE HAVE NOT BEEN REGISTERED
UNDER THE SECURITIES ACT OF 1933, AS AMENDED, AND MAY BE REOFFERED OR SOLD ONLY
IF SO REGISTERED OR IF AN EXEMPTION FROM SUCH REGISTRATION IS AVAILABLE. SUCH
SECURITIES ARE ALSO SUBJECT TO ADDITIONAL RESTRICTIONS ON TRANSFER AS SET FORTH
IN THE STOCK OPTION AGREEMENT, DATED AS OF APRIL 21, 1997, A COPY OF WHICH MAY
BE OBTAINED FROM CRA MANAGED CARE, INC.
 
    14. BINDING EFFECT; NO ASSIGNMENT. This Agreement shall be binding upon and
inure to the benefit of the parties hereto and their respective successors and
permitted assigns. Except as expressly provided for in this Agreement, neither
this Agreement nor the rights or the obligations of either party hereto are
assignable, except by operation of law, or with the written consent of the other
party. Nothing contained in this Agreement, express or implied, is intended to
confer upon any person other than the parties hereto and their respective
permitted assigns any rights or remedies of any nature whatsoever by reason of
this Agreement. Any Restricted Shares sold by a party in compliance with the
provisions of Section 10 or 11 shall, upon consummation of such sale, be free of
the restrictions imposed with respect to such shares by this Agreement, unless
and until such party shall repurchase or otherwise become the beneficial owner
of such shares, and any transferee of such shares shall not be entitled to the
rights of such party. Certificates representing shares sold in a registered
public offering pursuant to Section 11 shall not be required to bear the legend
set forth in Section 13.
 
    15. SPECIFIC PERFORMANCE. The parties recognize and agree that if for any
reason any of the provisions of this Agreement are not performed in accordance
with their specific terms or are otherwise breached, immediate and irreparable
harm or injury would be caused for which money damages would not be an adequate
remedy. Accordingly, each party agrees that, in addition to other remedies, the
other party shall be entitled to an injunction restraining any violation or
threatened violation of the provisions of this Agreement. In the event that any
action should be brought in equity to enforce the provisions of the Agreement,
neither party will allege, and each party hereby waives the defense, that there
is adequate remedy at law.
 
    16. ENTIRE AGREEMENT. This Agreement, the Confidentiality Agreement dated
March 19, 1997 between CRA and OSI (other than the "standstill" provisions
thereof, which are superseded pursuant to Section 10.4 of the Merger Agreement),
the Merger Agreement (including the exhibits and schedules thereto) and
 
                                      C-7
<PAGE>
the OSI Stock Option Agreement constitute the entire agreement among the parties
with respect to the subject matter hereof and supersede all other prior
agreements and understandings, both written and oral, among the parties or any
of them with respect to the subject matter hereof.
 
    17. FURTHER ASSURANCES. Each party will execute and deliver all such further
documents and instruments and take all such further action as may be necessary
in order to consummate the transactions contemplated hereby.
 
    18. VALIDITY. The invalidity or unenforceability of any provision of this
Agreement shall not affect the validity or enforceability of the other
provisions of this Agreement, which shall remain in full force and effect. In
the event any court or other competent authority holds any provision of this
Agreement to be null, void or unenforceable, the parties hereto shall negotiate
in good faith the execution and delivery of an amendment to this Agreement in
order, as nearly as possible, to effectuate, to the extent permitted by law, the
intent of the parties hereto with respect to such provision. Each party agrees
that, should any court or other competent authority hold any provision of this
Agreement or part hereof to be null, void or unenforceable, or order any party
to take any action inconsistent herewith, or not take any action required
herein, the other party shall not be entitled to specific performance of such
provision or part hereof or to any other remedy, including but not limited to
money damages, for breach hereof or of any other provision of this Agreement or
part hereof as the result of such holding or order.
 
    19. NOTICES. Any notice or communication required or permitted hereunder
shall be in writing and either delivered personally, telegraphed or telecopied
or sent by next day delivery by a nationally recognized overnight delivery
service or by certified or registered mail, postage prepaid, and shall be deemed
to be given, dated and received (i) when so delivered personally, (ii) upon
receipt of an appropriate electronic answer back or confirmation when so
delivered by telegraph or telecopy (to such number specified below or another
number or numbers as such person may subsequently designate by notice hereunder)
or (iii) one business day after sending by overnight delivery, and five business
days after the date of mailing by certified or registered mail, to the following
address or to such other address or addresses as such person may subsequently
designate by notice given hereunder, if so delivered by mail:
 
If to CRA:
 
CRA Managed Care, Inc.
312 Union Wharf
Boston, Massachusetts 02109
Attention: Chairman
Telecopier No.: (617) 720-1259
 
With copies to:
 
Hutchins, Wheeler & Dittmar
A Professional Corporation
101 Federal Street
Boston, MA 02110
Attention: James Westra, Esq.
Telecopier No.: (617) 951-1295
 
                                      C-8
<PAGE>
If to OSI:
 
OccuSystems, Inc.
3010 LBJ Freeway
Suite 400
Dallas, Texas 75234
Attention: General Counsel
Telecopier No.: (972) 243-7540
 
With copies to:
 
Vinson & Elkins LLP
2001 Ross Avenue
Suite 3700
Dallas, TX 75201
Attention: Jeffrey A. Chapman
Telecopier No.: (214) 220-7716
 
    20. GOVERNING LAW. This Agreement shall be governed by and construed in
accordance with the laws of the Commonwealth of Massachusetts applicable to
agreements made and to be performed entirely within such State.
 
    21. DESCRIPTIVE HEADINGS. The descriptive headings herein are inserted for
convenience of reference only and are not intended to be part of or to affect
the meaning or interpretation of this Agreement.
 
    22. COUNTERPARTS. This Agreement may be executed in two counterparts, each
of which shall be deemed to be an original, but both of which, taken together,
shall constitute one and the same instrument.
 
    23. EXPENSES. Except as otherwise expressly provided herein or in the Merger
Agreement, all costs and expenses incurred in connection with the transactions
contemplated by this Agreement shall be paid by the party incurring such
expenses.
 
    24. AMENDMENTS; WAIVER. This Agreement may be amended by the parties hereto
and the terms and conditions hereof may be waived only by an instrument in
writing signed on behalf of each of the parties hereto, or, in the case of a
waiver, by an instrument signed on behalf of the party waiving compliance.
 
    IN WITNESS WHEREOF, the parties hereto have caused this Agreement to be
executed by their respective duly authorized officers as of the date first above
written.
 
                                          OCCUSYSTEMS, INC.
 
                                          By: /s/ JOHN K. CARLYLE
- --------------------------------------------------------------------------------
                                            Title: CHAIRMAN & CHIEF EXECUTIVE
                                          OFFICER
 
                                          CRA MANAGED CARE, INC.
                                          By: /s/ DONALD J. LARSON
- --------------------------------------------------------------------------------
                                            Title: PRESIDENT & CHIEF EXECUTIVE
                                          OFFICER
 
                                      C-9
<PAGE>
                                   APPENDIX D
 
         OPINION OF DONALDSON, LUFKIN & JENRETTE SECURITIES CORPORATION
 
                                      D-1
<PAGE>
                                   APPENDIX E
 
                   OPINION OF ALEX. BROWN & SONS INCORPORATED
 
                                      E-1
<PAGE>
                                                                      APPENDIX F
 
                              CRA MERGER AGREEMENT
 
    THIS AGREEMENT AND PLAN OF MERGER (this "Agreement") is dated as of       ,
1997, by and between CRA Merger Corp., a Massachusetts corporation ("CRA Merger
Corp.") and a wholly-owned subsidiary of Concentra Managed Care, Inc., a
Delaware corporation ("Holding Company"), and CRA Managed Care, Inc., a
Massachusetts corporation ("CRA"). CRA and CRA Merger Corp. are sometimes
referred to herein as the "Constituent Corporations."
 
                                    RECITALS
 
    A. This Agreement is being entered into pursuant to an Agreement and Plan of
Reorganization dated as of April 21, 1997 (the "Reorganization Agreement"), by
and among CRA, OccuSystems, Inc., a Delaware corporation ("OccuSystems"), and
Holding Company. The Reorganization Agreement provides for, among other things,
(i) the merger of OccuSystems with and into Holding Company and (ii) the merger
of CRA Merger Corp. with and into CRA. All defined terms that are not otherwise
defined herein shall have the meaning ascribed to such terms in the
Reorganization Agreement.
 
    B. The number of outstanding shares of common stock, par value $.01 per
share, of CRA Merger Corp. is 100, all of which shares are of one class and all
of which shares are entitled to vote. The number of outstanding shares of the
common stock, par value $.01 per share, of CRA (the "CRA Common Stock") is
      , all of which shares are of one class and all of which shares are
entitled to vote.
 
    C. The respective Boards of Directors of CRA Merger Corp. and CRA have
approved this Agreement and have directed that this Agreement be submitted to a
vote of Holding Company, the sole stockholder of CRA Merger Corp, and the
stockholders of CRA.
 
    NOW, THEREFORE, in consideration of the mutual agreements and covenants set
forth herein, CRA Merger Corp. and CRA hereby agree, subject to the terms and
conditions hereinafter set forth, as follows:
 
                                   ARTICLE I
 
                                   THE MERGER
 
    SECTION 1.1 MERGER. In accordance with the provisions of this Agreement and
the Massachusetts Business Corporation Law (the "MBCL"), at the Effective Time
of the CRA Merger (as hereinafter defined) CRA Merger Corp. shall be merged with
and into CRA (the "CRA Merger"), the separate corporate existence of CRA Merger
Corp. shall cease and CRA will become a wholly-owned subsidiary of Holding
Company. CRA shall be the surviving corporation in the CRA Merger (hereinafter
sometimes referred to as the "Surviving Corporation") and shall continue its
corporate existence under the laws of the Commonwealth of Massachusetts.
 
    SECTION 1.2 FILING AND EFFECTIVENESS. The CRA Merger shall become effective
when the following actions have been completed: (a) the Reorganization Agreement
and the CRA Merger shall have been adopted and approved by the stockholders of
CRA and Holding Company, the sole stockholder of CRA Merger Corp., in accordance
with the requirements of the MBCL; and (b) an executed Articles of Merger shall
have been filed with the Secretary of State of the Commonwealth of
Massachusetts. The date and time when the CRA Merger shall become effective, as
hereinabove provided, is herein called the "Effective Time of the CRA Merger."
 
    SECTION 1.3 EFFECT OF THE MERGER. At the Effective Time of the CRA Merger,
(a) the separate existence of CRA Merger Corp. shall cease and CRA, as the
Surviving Corporation, shall possess all the rights, privileges, powers,
franchises and authority, both public and private, and be subject to all the
 
                                      F-1
<PAGE>
restrictions, disabilities and duties of the Constituent Corporation and (b) the
Surviving Corporation shall be vested with all assets and property, real,
personal and mixed, and every interest therein, wherever located, belonging to
each of the Constituent Corporations and shall be liable for all the obligations
and liabilities of each of the Constituent Corporations, all as more fully
provided under the applicable provisions of the MBCL.
 
                                   ARTICLE II
 
                   CHARTER DOCUMENTS, DIRECTORS AND OFFICERS
 
    SECTION 2.1 ARTICLES OF INCORPORATION. The Articles of Incorporation of CRA
Merger Corp. as in effect immediately prior to the Effective Time of the CRA
Merger shall be the Articles of Incorporation of the Surviving Corporation
immediately after the Effective Time of the CRA Merger.
 
    SECTION 2.2 BYLAWS. The Bylaws of CRA Merger Corp. as in effect immediately
prior to the Effective Time of the CRA Merger shall be the Bylaws of the
Surviving Corporation immediately after the Effective Time of the CRA Merger.
 
    SECTION 2.3 DIRECTORS AND OFFICERS. The directors and officers of CRA Merger
Corp. immediately prior to the Effective Time of the CRA Merger shall be the
directors and officers of the Surviving Corporation until their successors shall
have been duly elected and qualified in accordance with applicable law.
 
                                  ARTICLE III
 
                              CONVERSION OF STOCK
 
    SECTION 3.1 CRA COMMON STOCK. At the Effective Time of the CRA Merger, each
share of CRA Common Stock issued and outstanding immediately prior thereto
shall, by virtue of the CRA Merger and without any action by the Constituent
Corporations, the holder of such share or any other person, be converted into
the right to receive 1.786 (the "CRA Ratio") shares of Holding Company Common
Stock, payable upon the surrender of the certificates formerly representing CRA
Common Stock pursuant to Section 3.5. Each certificate which immediately prior
to the Effective Time of the CRA Merger represented outstanding shares of CRA
Common Stock shall, on and after the Effective Time of the CRA Merger, be deemed
for all purposes to represent the right to receive the number of shares of
Holding Company Common Stock into which the shares of CRA Common Stock
represented by such certificate shall have been converted pursuant to this
Section 3.1.
 
    SECTION 3.2 HOLDING COMPANY COMMON STOCK. At the Effective Time of the CRA
Merger, each share of Holding Company Common Stock issued and outstanding
immediately prior thereto shall, by virtue of the CRA Merger and without any
action by the Constituent Corporations, the holder of such share or any other
person, be canceled without payment of any consideration therefor and cease to
exist and be outstanding.
 
    SECTION 3.3 DISSENTING SHARES. Notwithstanding anything in this Article III
to the contrary, shares of CRA Common Stock which are issued and outstanding
immediately prior to the Effective Time of the CRA Merger and which are held by
stockholders who have not voted such shares in favor of the CRA Merger and who
shall have properly exercised their rights of appraisal for such shares in the
manner provided by the MBCL (the "Dissenting Shares") shall not be converted
into or be exchangeable for the right to receive shares of Holding Company
Common Stock pursuant to Section 3.1, unless and until such holder shall have
failed to perfect or shall have effectively withdrawn or lost his right to
appraisal and payment, as the case may be. If such holder shall have so failed
to perfect or shall have effectively withdrawn or lost such right, his shares
shall thereupon be deemed to have been converted into and to
 
                                      F-2
<PAGE>
have become exchangeable for, at the Effective Time of the CRA Merger, the right
to receive the shares of Holding Company Common Stock pursuant to Section 3.1,
without any interest thereon.
 
    SECTION 3.4 FRACTIONAL SHARES, ETC. No certificate of scrip representing
fractional shares of Holding Company Common Stock shall be issued upon the
surrender for exchange of Certificates. In lieu of any fractional shares, each
holder of shares of Converted Stock who would otherwise have been entitled to a
fraction of a share of Holding Company Common Stock upon surrender of
Certificates for exchange will be paid an amount of cash (without interest) in
accordance with the terms and conditions of Section 4.5 of the Reorganization
Agreement.
 
    SECTION 3.5 EXCHANGE FUND EXCHANGE PROCEDURES, ETC. The surrender and
exchange of Certificates for shares of Holding Company Common Stock shall be
made in accordance with the terms and conditions of Section 4.6 of the
Reorganization Agreement.
 
                                   ARTICLE IV
 
                                    GENERAL
 
    SECTION 4.1 FURTHER ASSURANCE. From time to time, as and when required by
the Surviving Corporation, or by its successors or assigns, there shall be
executed and delivered on behalf of CRA such deeds and other instruments, and
there shall be taken or caused to be taken by it such further and other actions
as shall be appropriate or necessary in order to vest or perfect in or confirm
of record or otherwise by Surviving Corporation the title to and possession of
all the property, interests, assets, rights, privileges, immunities, powers,
franchises and authority of CRA and otherwise to carry out the purposes of this
Agreement, and the officers and directors of the Surviving Corporation are fully
authorized in the name and on behalf of CRA or otherwise to take any and all
such action and to execute and deliver any and all such deeds and other
instruments.
 
    SECTION 4.2 TERMINATION. At any time before the Effective Time of the CRA
Merger, this Agreement may be terminated and the CRA Merger may be abandoned for
any reason whatsoever by the Board of Directors of either CRA or CRA Merger
Corp., or of both, notwithstanding the approval of this Agreement by the
stockholders of CRA or the sole stockholder of CRA Merger Corp. In the event of
the termination of this Agreement, this Agreement shall forthwith become void
and there shall be no liability on the part of either of the parties hereto
except as otherwise provided in the Reorganization Agreement.
 
    SECTION 4.3 COUNTERPARTS. In order to facilitate the filing and recording of
this Agreement, the same may be executed in any number of counterparts, each of
which shall be deemed to be an original and all of which together shall
constitute one and the same instrument.
 
    SECTION 4.4 AMENDMENT. This Agreement shall not be amended other than
pursuant to an amendment to the Reorganization Agreement approved in the manner
therein provided. If any such amendment to the Reorganization Agreement is so
approved, any amendment to this Agreement required by such amendment to the
Reorganization Agreement shall be effected by the parties hereto by action taken
by their respective Boards of Directors.
 
    SECTION 4.5 GOVERNING LAW. This Agreement shall be governed by the laws of
the Commonwealth of Massachusetts.
 
                                      F-3
<PAGE>
    IN WITNESS WHEREOF, this Agreement is hereby executed on behalf of each of
the Constituent Corporations.
 
                                        CRA MANAGED CARE, INC.
                                        a Massachusetts corporation
                                        By: ____________________________________
                                        Name: __________________________________
                                        Title: _________________________________
 
                                        CRA MERGER CORP.
                                        a Massachusetts corporation
                                        By: ____________________________________
                                        Name: __________________________________
                                        Title: _________________________________
 
                                      F-4
<PAGE>
                                   APPENDIX G
 
                          THE CONCENTRA INCENTIVE PLAN
 
                                      G-1
<PAGE>
                                   APPENDIX H
 
                   THE CONCENTRA EMPLOYEE STOCK PURCHASE PLAN
 
                                      H-1
<PAGE>
                                   APPENDIX I
 
          SECTIONS 86 TO 98 OF MASSACHUSETTS BUSINESS CORPORATION LAW
 
    86     RIGHT OF APPRAISAL.  If a corporation proposes to take a corporate
action as to which any section of this chapter provides that a stockholder who
objects to such action shall have the right to demand payment for his shares and
an appraisal thereof, sections eighty-seven to ninety-eight, inclusive, shall
apply except as otherwise specifically provided in any section of this chapter.
Except as provided in sections eighty-two and eighty-three, no stockholder shall
have such right unless (1) he files with the corporation BEFORE THE TAKING OF
THE VOTE OF THE SHAREHOLDERS ON SUCH CORPORATE ACTION, written objection to the
proposed action STATING THAT HE INTENDS TO DEMAND PAYMENT FOR HIS SHARES IF THE
ACTION IS TAKEN and (2) his shares are not voted in favor of the proposed
action.
 
    87     NOTICE OF STOCKHOLDERS MEETING TO CONTAIN STATEMENT AS TO APPRAISAL
RIGHTS.  The notice of the meeting of stockholders at which the approval of such
proposed action is to be considered shall contain a statement of the rights of
objecting stockholders. The giving of such notice shall not be deemed to create
any rights in any stockholder receiving the same to demand payment for his
stock, and the directors may authorize the inclusion in any such notice of a
statement of opinion by the management as to the existence or non-existence of
the right of the stockholders to demand payment for their stock on account of
the proposed corporate action. The notice may be in such form as the directors
or officers calling the meeting deem advisable, but the following form of notice
shall be sufficient to comply with this section:
 
      "If the action proposed is approved by the stockholders at the
      meeting and effected by the corporation, any stockholder (1) who
      files with the corporation BEFORE THE TAKING OF THE VOTE ON THE
      APPROVAL OF SUCH ACTION, WRITTEN OBJECTION TO THE PROPOSED ACTION
      STATING THAT HE INTENDS TO DEMAND PAYMENT FOR HIS SHARES IF THE
      ACTION IS TAKEN AND (2) WHOSE SHARES ARE NOT VOTED IN FAVOR OF SUCH
      ACTION HAS OR MAY HAVE THE RIGHT TO DEMAND IN WRITING FROM THE
      CORPORATION (OR, IN THE CASE OF A CONSOLIDATION OR MERGER, THE NAME
      OF THE RESULTING OR SURVIVING CORPORATION SHALL BE INSERTED), WITHIN
      TWENTY DAYS AFTER THE DATE OF MAILING TO HIM OF NOTICE IN WRITING
      THAT THE CORPORATE ACTION HAS BECOME EFFECTIVE, PAYMENT FOR HIS
      SHARES AND AN APPRAISAL OF THE VALUE THEREOF. Such corporation and
      any such stockholder shall in such cases have the rights and duties
      and shall follow the procedure set forth in sections 88 to 98,
      inclusive, of chapter 156B of the General Laws of Massachusetts."
 
    88     NOTICE TO OBJECTING STOCKHOLDER THAT CORPORATE ACTION HAS BECOME
EFFECTIVE.  The corporation taking such action, or in the case of a merger or
consolidation the surviving or resulting corporation, shall, within ten days
after the date on which such corporate action became effective, notify each
stockholder who filed written objection MEETING THE REQUIREMENTS OF SECTION
EIGHTY-SIX AND WHOSE SHARES WERE NOT VOTED IN FAVOR OF THE APPROVAL OF SUCH
ACTION, THAT THE ACTION APPROVED AT THE MEETING OF THE CORPORATION OF WHICH HE
IS A STOCKHOLDER HAS BECOME EFFECTIVE. THE GIVING OF SUCH NOTICE SHALL NOT BE
DEEMED TO CREATE ANY RIGHTS IN ANY STOCKHOLDER RECEIVING THE SAME TO DEMAND
PAYMENT FOR HIS STOCK. The notice shall be sent by registered or certified mail,
addressed to the stockholder at his last known address as it appears in the
records of the corporation.
 
    89     DEMAND FOR PAYMENT BY OBJECTING STOCKHOLDER.   If within twenty days
after the date of mailing a notice under subsection (e) of section eighty-two,
subsection (f) of section eighty-three, or section eighty-eight ANY STOCKHOLDER
TO WHOM THE CORPORATION WAS REQUIRED TO GIVE SUCH NOTICE SHALL demand in writing
from the corporation taking such action, or in the case of a consolidation or
merger from the resulting or surviving corporation, payment for his stock, the
corporation upon which such demand is made shall pay to him the fair value of
his stock within thirty days after the expiration of the period during which
such demand may be made.
 
                                      I-1
<PAGE>
    90    DETERMINATION OF VALUE OF STOCK BY SUPERIOR COURT.  If during the
period of thirty days provided for in section eighty-nine the corporation upon
which such demand is made and any such objecting stockholder fail to agree as to
the value of such stock, such corporation or any such stockholder may within
four months after the expiration of such thirty-day period demand a
determination of the value of the stock of all such objecting stockholders by a
bill in equity filed in the superior court in the county where the corporation
in which such objecting stockholder held stock had or has its principal office
in the commonwealth.
 
    91    BILL IN EQUITY TO DETERMINE VALUE OF STOCK OF OBJECTING STOCKHOLDERS
ON FAILURE TO AGREE ON VALUE THEREOF , ETC.;  PARTIES TO BILL ETC.; SERVICE OF
BILL ON CORPORATION; NOTICE TO STOCKHOLDER PARTIES, ETC. If the bill is filed by
the corporation, it shall name as parties respondent all stockholders who have
demanded payment for their shares and with whom the corporation has not reached
agreement as to the value thereof. If the bill is filed by a stockholder, he
shall bring the bill in his own behalf and in behalf of all other stockholders
who have demanded payment for their shares and with whom the corporation has not
reached agreement as to the value thereof, and service of the bill shall be made
upon the corporation by subpoena with a copy of the bill annexed. The
corporation shall file with its answer a duly verified list of all such other
stockholders, and such stockholders shall thereupon be deemed to have been added
as parties to the bill. The corporation shall give notice in such form and
returnable on such date as the court shall order to each stockholder party to
the bill by registered or certified mail, addressed to the last known address of
such stockholder as shown in the record of the corporation, and the court may
order such additional notice by publication or otherwise as it deems advisable.
Each stockholder who makes demand as provided in section eighty-nine shall be
deemed to have consented to the provisions of this section relating to notice,
and the giving of notice by the corporation to any such stockholder in
compliance with the order of the court shall be a sufficient service of process
on him. Failure to give notice to any stockholder making demand shall not
invalidate the proceedings as to other stockholders to whom notice was properly
given, and the court may at any time before the entry of a final decree make
supplementary orders of notice.
 
    92    BILL IN EQUITY TO DETERMINE VALUE OF STOCK OF OBJECTING STOCKHOLDERS
ON FAILURE TO AGREE ON VALUE THEREOF, ETC.; ENTRY OF DECREE DETERMINING VALUE OF
STOCK; DATE ON WHICH VALUE IS TO BE DETERMINED. After hearing the court shall
enter a decree determining the fair value of the stock of those stockholders who
have become entitled to the valuation of and payment for their shares, and shall
order the corporation to make payment of such value, together with interest, if
any, as hereinafter provided, to the stockholders entitled thereto upon the
transfer by them to the corporation of the certificates representing such stock
IF CERTIFICATED OR IF UNCERTIFICATED, UPON RECEIPT OF AN INSTRUCTION
TRANSFERRING SUCH STOCK TO THE CORPORATION. For this purpose, the value of the
shares shall be determined as of the day preceding the date of the vote
approving the proposed corporate action and shall be exclusive of any element of
value arising from the expectation or accomplishment of the proposed corporate
action.
 
    93    BILL IN EQUITY TO DETERMINE VALUE OF STOCK OF OBJECTING STOCKHOLDERS
ON FAILURE TO AGREE ON VALUE THEREOF, ETC.; COURT MAY REFER BILL, ETC., TO
SPECIAL MASTER TO HEAR PARTIES, ETC.   The court in its discretion may refer the
bill or any question arising thereunder to a special master to hear the parties,
make findings and report the same to the court, all in accordance with the usual
practice in suits in equity in the superior court.
 
    94    BILL IN EQUITY TO DETERMINE VALUE OF STOCK OF OBJECTING STOCKHOLDERS
ON FAILURE TO AGREE ON VALUE THEREOF, ETC.; STOCKHOLDER PARTIES MAY BE REQUIRED
TO SUBMIT THEIR STOCK CERTIFICATES FOR NOTATION THEREON OF PENDENCY OF BILL,
ETC.   On motion the court may order stockholder parties to the bill to submit
their certificates of stock to the corporation for notation thereon of the
pendency of the bill, and MAY ORDER THE CORPORATION TO NOTE SUCH PENDENCY IN ITS
RECORDS WITH RESPECT TO ANY UNCERTIFICATED SHARES HELD BY SUCH STOCKHOLDER
PARTIES, and may on motion dismiss the bill as to any stockholder who fails to
comply with such order.
 
                                      I-2
<PAGE>
    95    BILL IN EQUITY TO DETERMINE VALUE OF STOCK OF OBJECTING STOCKHOLDERS
ON FAILURE TO AGREE ON VALUE THEREOF, ETC.; TAXATION OF COSTS, ETC.; INTEREST ON
AWARD, ETC.   The costs of the bill, including the reasonable compensation and
expenses of any master appointed by the court, but exclusive of fees of counsel
or of experts retained by any party, shall be determined by the court and taxed
upon the parties to the bill, or any of them, in such manner as appears to be
equitable, except that all costs of giving notice to stockholders as provided in
this chapter shall be paid by the corporation. Interest shall be paid upon any
award from the date of the vote approving the proposed corporate action, and the
court may on application of any interested party determine the amount of
interest to be paid in the case of any stockholder.
 
    96    STOCKHOLDER DEMANDING PAYMENT FOR STOCK NOT ENTITLED TO NOTICE OF
STOCKHOLDERS' MEETINGS OR TO VOTE STOCK OR TO RECEIVE DIVIDENDS, ETC.;
EXCEPTIONS.   Any stockholder who has demanded payment for his stock as provided
in this chapter shall not thereafter be entitled to notice of any meeting of
stockholders or to vote such stock for any purpose and shall not be entitled to
the payment of dividends or other distribution on the stock (except dividends or
other distributions payable to stockholders of record at a date which is prior
to the date of the vote approving the proposed corporate action) unless:
 
        (1) A bill shall not be filed within the time provided in section
    ninety;
 
        (2) A bill, if filed, shall be dismissed as to such stockholder; or
 
        (3) Such stockholder shall with the written approval of the corporation,
    or in the case of a consolidation or merger, the resulting or surviving
    corporation, deliver to it a written withdrawal of his objections to and an
    acceptance of such corporate action.
 
    NOTWITHSTANDING THE PROVISIONS OF CLAUSES (1) TO (3), INCLUSIVE, SAID
STOCKHOLDER SHALL HAVE ONLY THE RIGHTS OF A STOCKHOLDER WHO DID NOT SO DEMAND
PAYMENT FOR HIS STOCK AS PROVIDED IN THIS CHAPTER.
 
    97    CERTAIN SHARES PAID FOR BY CORPORATION TO HAVE STATUS OF TREASURY
STOCK, ETC.   The shares of the corporation paid for by the corporation pursuant
to the provisions of this chapter shall have the status of treasury stock or in
the case of a consolidation or merger the shares or the securities of the
resulting or surviving corporation into which the shares of such objecting
stockholder would have been converted had he not objected to such consolidation
or merger shall have the status of treasury stock or securities.
 
    98    ENFORCEMENT BY STOCKHOLDER OF RIGHT TO RECEIVE PAYMENT FOR HIS SHARES
TO BE EXCLUSIVE REMEDY; EXCEPTION.   The enforcement by a stockholder of his
right to receive payment for his shares in the manner provided in this chapter
shall be an exclusive remedy except that this chapter shall not exclude the
right of such stockholder to bring or maintain an appropriate proceeding to
obtain relief on the ground that such corporate action will be or is illegal or
fraudulent as to him.
 
                                      I-3
<PAGE>
                                    PART II
 
                     INFORMATION NOT REQUIRED IN PROSPECTUS
 
ITEM 20. INDEMNIFICATION OF DIRECTORS AND OFFICERS
 
    Article Eleventh of the Certificate of Incorporation of the Registrant
provides that the Registrant shall indemnify its directors and officers to the
maximum extent allowed by the Delaware General Corporation Law. Pursuant to
Section 145 of the Delaware General Corporation Law, the Registrant generally
has the power to indemnify its present and former directors and officers against
expenses and liabilities incurred by them in connection with any suit to which
they are, or are threatened to be made, a party by reason of their serving in
those positions so long as they acted in good faith and in a manner they
reasonably believed to be in, or not opposed to, the best interests of the
Registrant, and with respect to any criminal action, so long as they had no
reasonable cause to believe their conduct was unlawful. With respect to suits by
or in the right of the Registrant, however, indemnification is generally limited
to attorneys' fees and other expenses and is not available if the person is
adjudged to be liable to the Registrant, unless the court determines that
indemnification is appropriate. The statute expressly provides that the power to
indemnify authorized thereby is not exclusive of any rights granted under any
bylaw, agreement, vote of stockholders or disinterested directors, or otherwise.
The Registrant also has the power to purchase and maintain insurance for its
directors and officers and has recently obtained such insurance. Additionally,
Article Eleventh of the Certificate of Incorporation provides that, in the event
that an officer or director files suit against the Registrant seeking
indemnification of liabilities or expenses incurred, the burden will be on the
Registrant to prove that the indemnification would not be permitted under the
Delaware General Corporation Law.
 
    The preceding discussion of the Registrant's Restated Certificate of
Incorporation and Section 145 of the Delaware General Corporation Law is not
intended to be exhaustive and is qualified in its entirety by the Certificate of
Incorporation and Section 145 of the Delaware General Corporation Law.
 
    The Registrant intends to enter into indemnity agreements with the
Registrant's directors and officers. Pursuant to such agreements, the Registrant
will, to the extent permitted by applicable law, indemnify such persons against
all expenses, judgments, fines and penalties incurred in connection with the
defense or settlement of any actions brought against them by reason of the fact
that they were directors or officers of the Registrant or assumed certain
responsibilities at the direction of the Registrant.
 
ITEM 21. EXHIBITS AND FINANCIAL STATEMENT SCHEDULES.
 
<TABLE>
<CAPTION>
     EXHIBIT
     NUMBER                                            DESCRIPTION OF EXHIBITS
- -----------------  -----------------------------------------------------------------------------------------------
<C>                <S>
            2.1    Agreement and Plan of Reorganization dated April 21, 1997 among CRA Managed Care, Inc. ("CRA"),
                   OccuSystems, Inc. ("OccuSystems") and the Registrant (filed as Appendix A to the Joint Proxy
                   Statement/Prospectus forming a part of this Registration Statement).
            3.1    Certificate of Incorporation dated April 21, 1997 of Registrant.
            3.2    Bylaws of Registrant.
           *4.1    Specimen Certificate for the Common Stock.
           *5.1    Opinion of Vinson & Elkins L.L.P. as to the legality of the securities to be registered.
           *8.1    Opinion of Vinson & Elkins L.L.P. as to federal income tax consequences.
           *8.2    Opinion of Hutchins, Wheeler & Dittmar, A Professional Corporation, as to federal income tax
                   consequences.
         --10.1    Indenture dated as of December 24, 1996, between OccuSystems and U.S. Trust Company of Texas,
                   N.A.
</TABLE>
 
                                      II-1
<PAGE>
<TABLE>
<CAPTION>
     EXHIBIT
     NUMBER                                            DESCRIPTION OF EXHIBITS
- -----------------  -----------------------------------------------------------------------------------------------
<C>                <S>
          *10.2    Form of Rights Agreement to be entered into between the Registrant and .
          *10.3    Form of Employment Agreement to be entered into between the Registrant and each of its
                   executive officers.
          *10.4    Form of Indemnification Agreement to be entered into between the Registrant and each of its
                   executive officers and directors.
          *10.5    Concentra Managed Care, Inc. Long-Term Incentive Plan (filed as Appendix G to the Joint Proxy
                   Statement/Prospectus forming a part of this Registration Statement).
          *10.6    Concentra Managed Care, Inc. Employee Stock Purchase Plan (to be filed as Appendix H to the
                   Joint Proxy Statement/Prospectus forming a part of this Registration Statement).
          *10.7    Agreement dated as of            , 1997, between the Registrant and Lois E. Silverman.
          *10.8    Agreement dated as of            , 1997, between the Registrant and Richard D. Rehm, M.D.
           10.9    OccuSystems, Inc. Stock Option Agreement dated as of April 21, 1997 (filed as Appendix B to the
                   Joint Proxy Statement/Prospectus forming a part of this Registration Statement).
           10.10   CRA Managed Care, Inc. Stock Option Agreement dated as of April 21, 1997 (filed as Appendix C
                   to the Joint Proxy Statement/Prospectus forming a part of this Registration Statement).
         --10.11   OccuSystems, Inc. 1995 Long-Term Incentive Plan.
          *10.12   Agreement of Acceptance, dated as of , 1997 among Concentra, Donald J. Larson and Lois E.
                   Silverman.
         ++10.13   CRA 1995 Employee Stock Purchase Plan.
         ++10.14   CRA 1994 Non-Qualified Stock Option Plan for Non-Employee Directors.
         ++10.15   Form of Non-Qualified Stock Option Agreement pursuant to the CRA 1994 Non-Qualified Option Plan
                   for Non-Employee Directors.
         ++10.16   CRA 1994 Non-Qualified Time Accelerated Restricted Stock Option Plan.
         ++10.17   Form of Non-Qualified Stock Option Agreement pursuant to the CRA 1994 Non-Qualified Time
                   Accelerated Restricted Stock Option Plan.
         ++10.18   Software License Agreement between CompReview, Inc. and CRA, dated February 10, 1995
                   (confidential treatment granted).
          +10.19   Lease Agreement, dated January 1, 1994, by and between Colonial Realty Trust and CRA for office
                   space located at 168 U.S. Route 1, Falmouth, ME 04105.
          +10.20   Lease Agreement, dated January 1, 1994, by and between Colonial Realty Trust and CRA for office
                   space located at 46 Austin Street, Newtonville, MA 02160.
          +10.21   Lease Agreement, dated January 1, 1994, by and between Colonial Realty Trust and CRA for office
                   space located at 312 Union Wharf, Boston, MA 02109.
          +10.22   Lease Agreement, dated January 1, 1994, by and between Colonial Realty Trust and CRA for office
                   space located at 565 Turnpike Street, North Andover, MA 01845.
          +10.23   Lease Agreement, dated January 1, 1994, by and between Colonial Realty Trust and CRA for office
                   space located at 15A Riverway Place, Bedford, NH 03110.
          +10.24   Lease Agreement, dated January 1, 1994, by and between Colonial Realty Trust and CRA for office
                   space located at 509 Stillwells Corner Road, Freehold, NJ 07728.
          +10.25   Lease Agreement, dated January 1, 1994, by and between Colonial Realty Trust and CRA for office
                   space located at 732 Thimble Shoals Blvd., Newport News, VA 23606.
          +10.26   Lease Agreement, dated January 1, 1994, by and between Colonial Realty Trust and CRA for office
                   space located at 10132 Colvin Run Road, Suite A, Great Falls, VA 22066.
</TABLE>
 
                                      II-2
<PAGE>
<TABLE>
<CAPTION>
     EXHIBIT
     NUMBER                                            DESCRIPTION OF EXHIBITS
- -----------------  -----------------------------------------------------------------------------------------------
<C>                <S>
          -10.27   Occupational Medicine Center Management and Consulting Agreement dated December 31, 1993,
                   between OccuCenters, Inc. ("OCI") and Occupational Health Centers of Southwest, P.A., a Texas
                   professional association.
          -10.28   Occupational Medicine Center Management and Consulting Agreement dated December 31, 1993,
                   between OCI and Occupational Health Centers of the Southwest, P.A., an Arizona professional
                   association.
         --10.29   Form of Occupational Medicine Center Management and Consulting Agreement dated December 31,
                   1993, between OCI and Occupational Health Centers of New Jersey, P.A., a New Jersey
                   professional association, to be entered into by OCI and Occupational Health Centers of New
                   Jersey, P.A.
        ---10.30   Amended and Restated Loan and Security Agreement dated January 3, 1995, among the Company, OCI
                   and the lenders named therein, and Creditanstalt-Bankverein, as Agent for the Lenders, together
                   with all amendments thereto.
        ---10.31   Form of OccuSystems, Inc. 1995 Long-Term Incentive Plan.
        ---10.32   First Amended and Restated OccuSystems, Inc. and its Subsidiaries and Affiliates Stock Option
                   and Restricted Stock Purchase Plan dated April 28, 1992.
        ---10.33   Form of Indemnification Agreement entered into between OccuSystems, Inc. and its executive
                   officers and directors.
        ---10.34   Warrant Agreement dated January 3, 1995, between the Company and Creditanstalt-Bankverein.
          *21.1    Subsidiaries of the Registrant.
          *23.1    Consent of Vinson & Elkins L.L.P. (set forth in Exhibit 5.1).
          *23.2    Consent of Hutchins, Wheeler & Dittmar, A Professional Corporation (set forth in Exhibit 8.2).
           23.3    Consent of Arthur Andersen LLP, Independent Auditors.
           23.4    Consent of Arthur Andersen LLP, Independent Auditors.
           24.1    The power of attorney of officers and directors of the Registrant is set forth on the signature
                   page of this Registration Statement.
           99.1    Consent of Robert W. O'Leary to be named as a director of the Registrant in this Registration
                   Statement.
           99.2    Consent of Robert A. Ortenzio to be named as a director of the Registrant in this Registration
                   Statement.
           99.3    Consent of Paul B. Queally to be named as a director of the Registrant in this Registration
                   Statement.
           99.4    Consent of Lois E. Silverman to be named as a director of the Registrant in this Registration
                   Statement.
           99.5    Consent of George H. Conrades to be named as a director of the Registrant in this Registration
                   Statement.
           99.6    Consent of Mitchell T. Rabkin, M.D. to be named as a director of the Registrant in this
                   Registration Statement.
           99.7    Consent of Donaldson, Lufkin & Jenrette Securities Corporation.
           99.8    Consent of Alex. Brown & Sons Incorporated.
          *99.9    Form of Proxy for Special Meeting of Stockholders of OccuSystems.
          *99.10   Form of Proxy for Special Meeting of Stockholders of CRA.
</TABLE>
 
- ------------------------
 
*   To be filed by amendment
 
+   Incorporated by reference to CRA's Registration Statement on Form S-3 (File
    No. 33-90426), as filed on November 7, 1996
 
                                      II-3
<PAGE>
++  Incorporated by reference to CRA's Registration Statement on Form S-1 (File
    No. 33-90426), as filed on March 17, 1995.
 
- -   Incorporated by reference to OccuSystems' Annual Report on Form 10-K (File
    No. 0-24440), as filed on March 29, 1996.
 
- --  Incorporated by reference to OccuSystems' Annual Report on Form 10-K (File
    No. 33-79734), as filed on March 31, 1997.
 
- ---  Incorporated by reference to OccuSystems' Registration Statement on Form
    S-1 (File No. 33-01660), as filed on March 27, 1996.
 
ITEM 22. UNDERTAKINGS.
 
    The undersigned Registrant hereby undertakes:
 
        (1) To file, during any period in which offers or sales are being made,
    a post-effective amendment to this Registration Statement:
 
            (i) To include any prospectus required in Section 10(a) (3) of the
       Securities Act of 1933, as amended (the "Securities Act");
 
            (ii) To reflect in the prospectus any facts of events arising after
       the effective date of the registration statement (or the most recent
       post-effective amendment thereof) which, individually or in the
       aggregate, represent a fundamental change in the information set forth in
       the registration statement. Notwithstanding the foregoing, any increase
       or decrease in volume of securities offered (if the total dollar value of
       securities offered would not exceed that which was registered) and any
       deviation from the low or high end of the estimated maximum offering
       range may be reflected in the form of prospectus filed with the
       Commission pursuant to Rule 424(b) (Section 230.424(b) of this chapter)
       if, in the aggregate, the changes in volume and price represent no more
       than a 20% change in the maximum aggregate offering price set forth in
       the "Calculation of Registration Fee" table in the effective registration
       statement; and
 
           (iii) To include any material information with respect to the plan of
       distribution not previously disclosed in the Registration Statement or
       any material change to such information in the Registration Statement.
 
        (2) That, for the purpose of determining any liability under the
    Securities Act, each such post-effective amendment shall be deemed to be a
    new registration statement relating to the securities offered therein, and
    the offering of such securities at that time shall be deemed to be the
    initial bona fide offering thereof.
 
        (3) To remove from registration by means of a post-effective amendment
    any of the securities being registered which remain unsold at the
    termination of the offering.
 
        (4) That, for purposes of determining any liability under the Securities
    Act, each filing of the Registrant's annual report pursuant to section 13(a)
    or section 15(d) of the Exchange Act that is incorporated by reference in
    the Registration Statement shall be deemed to be a new registration
    statement relating to the securities offered therein, and the offering of
    such securities at that time shall be deemed to be the initial bona fide
    offering thereof.
 
        (5) Insofar as indemnification for liabilities arising under the
    Securities Act may be permitted to directors, officers and controlling
    persons of the Registrant pursuant to the provisions described under Item 20
    above, or otherwise, the Registrant has been advised that in the opinion of
    the Securities and Exchange Commission such indemnification is against
    public policy as expressed in the Securities Act and is, therefore,
    unenforceable. In the event that a claim for indemnification against such
    liabilities
 
                                      II-4
<PAGE>
    (other than the payment by the Registrant of expenses incurred or paid by a
    director, officer or controlling person of the Registrant in the successful
    defense of any action, suit or proceeding) is asserted by such director,
    officer or controlling person in connection with the securities being
    registered, the Registrant will, unless in the opinion of its counsel the
    matter has been settled by controlling precedent, submit to a court of
    appropriate jurisdiction the question whether such indemnification by it is
    against public policy as expressed in the Securities Act and will be
    governed by the final adjudication of such issue.
 
        (6) The undersigned registrant hereby undertakes to respond to requests
    for information that is incorporated by reference into the prospectus
    pursuant to Items 4, 10(b), 11, or 13 of this Form, within one business day
    of receipt of such request, and to send the incorporated documents by first
    class mail or other equally prompt means. This includes information
    contained in documents filed subsequent to the effective date of the
    registration statement through the date of responding to the request.
 
        (7) The undersigned registrant hereby undertakes to supply by means of
    post-effective amendment all information by means of a post-effective
    amendment all information concerning a transaction, and the company being
    acquired involved therein, that was not the subject of and included in the
    registration statement when it became effective.
 
                                      II-5
<PAGE>
                                   SIGNATURES
 
    Pursuant to the requirements of the Securities Act of 1933, the Registrant
has duly caused this Registration Statement to be signed on its behalf by the
undersigned, thereunto duly authorized in the City of Boston, Commonwealth of
Massachusetts, on May 14, 1997.
 
                                CONCENTRA MANAGED CARE, INC.
 
                                By:             /s/ DONALD J. LARSON
                                     -----------------------------------------
                                                  Donald J. Larson
                                       PRESIDENT AND CHIEF EXECUTIVE OFFICER
 
    KNOW ALL MEN BY THESE PRESENTS,  that each person whose signature appears
below constitutes and appoints John K. Carlyle, Donald J. Larson and Richard A.
Parr II, or any of them, his true and lawful attorney-in-fact and agent, with
full power of substitution, for him and his name, place and stead, in any and
all capacities, to sign any and all amendments (including post-effective
amendments) to this Registration Statement, and to file the same with all
exhibits thereto, and other documents in connection therewith, with the
Securities and Exchange Commission, granting unto said attorney-in-fact and
agent full power and authority to do and perform each and every act and thing
requisite and ratifying and confirming all that said attorney-in-fact and agent
or his substitute or substitutes may lawfully do or cause to be done by virtue
thereof.
 
    Pursuant to the requirements of the Securities Act of 1933, this
Registration Statement has been signed by the following persons in the
capacities indicated on the dates indicated.
 
          SIGNATURE                        TITLE                    DATE
- ------------------------------  ---------------------------  -------------------
 
     /s/ JOHN K. CARLYLE        Chairman of the Board
- ------------------------------                                  May 14, 1997
       John K. Carlyle
                                Director, President and
     /s/ DONALD J. LARSON         Chief Executive Officer
- ------------------------------    (Principal Executive          May 14, 1997
       Donald J. Larson           Officer)
                                Executive Vice President
     /s/ JOSEPH F. PESCE          and Chief Financial
- ------------------------------    Officer                       May 14, 1997
       Joseph F. Pesce            (Principal Financial and
                                  Accounting Officer)
 
                                      II-6
<PAGE>
                                 EXHIBIT INDEX
 
<TABLE>
<CAPTION>
     EXHIBIT
     NUMBER                                            DESCRIPTION OF EXHIBITS
- -----------------  -----------------------------------------------------------------------------------------------
<C>                <S>
            2.1    Agreement and Plan of Reorganization dated April 21, 1997 among CRA Managed Care, Inc. ("CRA"),
                   OccuSystems, Inc. ("OccuSystems") and the Registrant (filed as Appendix A to the Joint Proxy
                   Statement/Prospectus forming a part of this Registration Statement).
            3.1    Certificate of Incorporation dated April 21, 1997 of Registrant.
            3.2    Bylaws of Registrant.
           *4.1    Specimen Certificate for the Common Stock.
           *5.1    Opinion of Vinson & Elkins L.L.P. as to the legality of the securities to be registered.
           *8.1    Opinion of Vinson & Elkins L.L.P. as to federal income tax consequences.
           *8.2    Opinion of Hutchins, Wheeler & Dittmar, A Professional Corporation, as to federal income tax
                   consequences.
         --10.1    Indenture dated as of December 24, 1996, between OccuSystems and U.S. Trust Company of Texas,
                   N.A.
          *10.2    Form of Rights Agreement to be entered into between the Registrant and .
          *10.3    Form of Employment Agreement to be entered into between the Registrant and each of its
                   executive officers.
          *10.4    Form of Indemnification Agreement to be entered into between the Registrant and each of its
                   executive officers and directors.
          *10.5    Concentra Managed Care, Inc. Long-Term Incentive Plan (filed as Appendix G to the Joint Proxy
                   Statement/Prospectus forming a part of this Registration Statement).
          *10.6    Concentra Managed Care, Inc. Employee Stock Purchase Plan (to be filed as Appendix H to the
                   Joint Proxy Statement/Prospectus forming a part of this Registration Statement).
          *10.7    Agreement dated as of            , 1997, between the Registrant and Lois E. Silverman.
          *10.8    Agreement dated as of            , 1997, between the Registrant and Richard D. Rehm, M.D.
           10.9    OccuSystems, Inc. Stock Option Agreement dated as of April 21, 1997 (filed as Appendix B to the
                   Joint Proxy Statement/Prospectus forming a part of this Registration Statement).
           10.10   CRA Managed Care, Inc. Stock Option Agreement dated as of April 21, 1997 (filed as Appendix C
                   to the Joint Proxy Statement/Prospectus forming a part of this Registration Statement).
         --10.11   OccuSystems, Inc. 1995 Long-Term Incentive Plan.
          *10.12   Agreement of Acceptance, dated as of , 1997 among Concentra, Donald J. Larson and Lois E.
                   Silverman.
         ++10.13   CRA 1995 Employee Stock Purchase Plan.
         ++10.14   CRA 1994 Non-Qualified Stock Option Plan for Non-Employee Directors.
         ++10.15   Form of Non-Qualified Stock Option Agreement pursuant to the CRA 1994 Non-Qualified Option Plan
                   for Non-Employee Directors.
         ++10.16   CRA 1994 Non-Qualified Time Accelerated Restricted Stock Option Plan.
         ++10.17   Form of Non-Qualified Stock Option Agreement pursuant to the CRA 1994 Non-Qualified Time
                   Accelerated Restricted Stock Option Plan.
         ++10.18   Software License Agreement between CompReview, Inc. and CRA, dated February 10, 1995
                   (confidential treatment granted).
          +10.19   Lease Agreement, dated January 1, 1994, by and between Colonial Realty Trust and CRA for office
                   space located at 168 U.S. Route 1, Falmouth, ME 04105.
          +10.20   Lease Agreement, dated January 1, 1994, by and between Colonial Realty Trust and CRA for office
                   space located at 46 Austin Street, Newtonville, MA 02160.
</TABLE>
<PAGE>
<TABLE>
<CAPTION>
     EXHIBIT
     NUMBER                                            DESCRIPTION OF EXHIBITS
- -----------------  -----------------------------------------------------------------------------------------------
<C>                <S>
          +10.21   Lease Agreement, dated January 1, 1994, by and between Colonial Realty Trust and CRA for office
                   space located at 312 Union Wharf, Boston, MA 02109.
          +10.22   Lease Agreement, dated January 1, 1994, by and between Colonial Realty Trust and CRA for office
                   space located at 565 Turnpike Street, North Andover, MA 01845.
          +10.23   Lease Agreement, dated January 1, 1994, by and between Colonial Realty Trust and CRA for office
                   space located at 15A Riverway Place, Bedford, NH 03110.
          +10.24   Lease Agreement, dated January 1, 1994, by and between Colonial Realty Trust and CRA for office
                   space located at 509 Stillwells Corner Road, Freehold, NJ 07728.
          +10.25   Lease Agreement, dated January 1, 1994, by and between Colonial Realty Trust and CRA for office
                   space located at 732 Thimble Shoals Blvd., Newport News, VA 23606.
          +10.26   Lease Agreement, dated January 1, 1994, by and between Colonial Realty Trust and CRA for office
                   space located at 10132 Colvin Run Road, Suite A, Great Falls, VA 22066.
          -10.27   Occupational Medicine Center Management and Consulting Agreement dated December 31, 1993,
                   between OccuCenters, Inc. ("OCI") and Occupational Health Centers of Southwest, P.A., a Texas
                   professional association.
          -10.28   Occupational Medicine Center Management and Consulting Agreement dated December 31, 1993,
                   between OCI and Occupational Health Centers of the Southwest, P.A., an Arizona professional
                   association.
         --10.29   Form of Occupational Medicine Center Management and Consulting Agreement dated December 31,
                   1993, between OCI and Occupational Health Centers of New Jersey, P.A., a New Jersey
                   professional association, to be entered into by OCI and Occupational Health Centers of New
                   Jersey, P.A.
        ---10.30   Amended and Restated Loan and Security Agreement dated January 3, 1995, among the Company, OCI
                   and the lenders named therein, and Creditanstalt-Bankverein, as Agent for the Lenders, together
                   with all amendments thereto.
        ---10.31   Form of OccuSystems, Inc. 1995 Long-Term Incentive Plan.
        ---10.32   First Amended and Restated OccuSystems, Inc. and its Subsidiaries and Affiliates Stock Option
                   and Restricted Stock Purchase Plan dated April 28, 1992.
        ---10.33   Form of Indemnification Agreement entered into between OccuSystems, Inc. and its executive
                   officers and directors.
        ---10.34   Warrant Agreement dated January 3, 1995, between the Company and Creditanstalt-Bankverein.
          *21.1    Subsidiaries of the Registrant.
          *23.1    Consent of Vinson & Elkins L.L.P. (set forth in Exhibit 5.1).
          *23.2    Consent of Hutchins, Wheeler & Dittmar, A Professional Corporation (set forth in Exhibit 8.2).
           23.3    Consent of Arthur Andersen LLP, Independent Auditors.
           23.4    Consent of Arthur Andersen LLP, Independent Auditors.
           24.1    The power of attorney of officers and directors of the Registrant is set forth on the signature
                   page of this Registration Statement.
           99.1    Consent of Robert W. O'Leary to be named as a director of the Registrant in this Registration
                   Statement.
           99.2    Consent of Robert A. Ortenzio to be named as a director of the Registrant in this Registration
                   Statement.
           99.3    Consent of Paul B. Queally to be named as a director of the Registrant in this Registration
                   Statement.
           99.4    Consent of Lois E. Silverman to be named as a director of the Registrant in this Registration
                   Statement.
           99.5    Consent of George H. Conrades to be named as a director of the Registrant in this Registration
                   Statement.
</TABLE>
<PAGE>
<TABLE>
<CAPTION>
     EXHIBIT
     NUMBER                                            DESCRIPTION OF EXHIBITS
- -----------------  -----------------------------------------------------------------------------------------------
<C>                <S>
           99.6    Consent of Mitchell T. Rabkin, M.D. to be named as a director of the Registrant in this
                   Registration Statement.
           99.7    Consent of Donaldson, Lufkin & Jenrette Securities Corporation.
           99.8    Consent of Alex. Brown & Sons Incorporated.
          *99.9    Form of Proxy for Special Meeting of Stockholders of OccuSystems.
          *99.10   Form of Proxy for Special Meeting of Stockholders of CRA.
</TABLE>
 
- ------------------------
 
*   To be filed by amendment
 
+   Incorporated by reference to CRA's Registration Statement on Form S-3 (File
    No. 33-90426), as filed on November 7, 1996
 
++  Incorporated by reference to CRA's Registration Statement on Form S-1 (File
    No. 33-90426), as filed on March 17, 1995.
 
- -   Incorporated by reference to OccuSystems' Annual Report on Form 10-K (File
    No. 0-24440), as filed on March 29, 1996.
 
- --  Incorporated by reference to OccuSystems' Annual Report on Form 10-K (File
    No. 33-79734), as filed on March 31, 1997.
 
- ---  Incorporated by reference to OccuSystems' Registration Statement on Form
    S-1 (File No. 33-01660), as filed on March 27, 1996.
<PAGE>
                                                                     EXHIBIT 3.1
 
                          CERTIFICATE OF INCORPORATION
                                       OF
                          CONCENTRA MANAGED CARE, INC.
 
    FIRST:  The name of the corporation is Concentra Managed Care, Inc.
 
    SECOND:  The address of its registered office in the State of Delaware is
Corporation Trust Center, 1209 Orange Street, Wilmington, Delaware 19801 in New
Castle County, Delaware. The name of its registered agent at such address is The
Corporation Trust Company.
 
    THIRD:  The nature of the business or purposes to be conducted or promoted
by the corporation is to engage in any lawful act or activity for which
corporations may be organized under the Delaware General Corporation Law.
 
    FOURTH:  The total number of shares of all classes of stock which the
corporation shall have authority to issue is One Hundred and Twenty (120), of
which (a) One Hundred (100) shares shall be designated as Common Stock, par
value $0.01 per share, and (b) Twenty (20) shares shall be designated as
Preferred Stock, par value $1.00 per share.
 
    The following is a statement of the designations, preferences, limitations
and relative rights, including voting rights in respect of the classes of stock
of the Corporation and of the authority with respect thereto expressly vested in
the Board of Directors of the Corporation:
 
    A. COMMON STOCK
 
    1. Each share of Common Stock of the Corporation shall have identical rights
and privileges in every respect. The holders of shares of Common Stock shall be
entitled to vote upon all matters submitted to a vote of the stockholders of the
Corporation and shall be entitled to one vote for each share of Common Stock
held.
 
    2. Subject to the prior rights and preferences, if any, applicable to shares
of the Preferred Stock or any series thereof, the holders of shares of the
Common Stock shall be entitled to receive such dividends (payable in cash, stock
or otherwise) as may be declared thereon by the Board of Directors at any time
and from time to time out of any funds of the Corporation legally available
therefor.
 
    3. In the event of any voluntary or involuntary liquidation, dissolution or
winding-up of the Corporation, after distribution in full of the preferential
amounts, if any, to be distributed to the holders of shares of the Preferred
Stock or any series thereof, the holders of shares of the Common Stock shall be
entitled to receive all of the remaining assets of the Corporation available for
distribution to its stockholders, ratably in proportion to the number of shares
of the Common Stock held by them. A liquidation, dissolution or winding-up of
the Corporation, as such terms are used in this Paragraph (3), shall not be
deemed to be occasioned by or to include any merger of the Corporation with or
into one or more corporations or other entities, any acquisition or exchange of
the outstanding shares of one or more classes or series of the Corporation or
any sale, lease, exchange or other disposition of all or a part of the assets of
the Corporation.
 
    B. PREFERRED STOCK
 
    1. Shares of the Preferred Stock may be issued from time to time in one or
more series, the shares of each series to have such voting powers, designations,
preferences, rights and qualifications, limitations or restrictions, as shall be
stated and expressed herein or in a resolution or resolutions providing for the
issue
 
                                       1
<PAGE>
of such series adopted by the Board of Directors of the Corporation (or a duly
authorized committee thereof). Each such series of Preferred Stock shall be
designated so as to distinguish the shares thereof from the shares of all other
series and classes. The Board of Directors of the Corporation (or a duly
authorized committee thereof) is hereby expressly authorized, subject to the
limitations provided by law, to establish and designate series of the Preferred
Stock, to fix the number of shares constituting each series and to fix the
voting powers, designations, preferences, rights and qualifications, limitations
or restrictions of the shares of each series and the variations of the relative
rights and preferences as between series, and to increase and to decrease the
number of shares constituting each series, provided that the Board of Directors
(or a duly authorized committee thereof) may not decrease the number of shares
within a series to less than the number of shares within such series that are
then issued. The relative powers, preferences, rights and qualifications,
limitation or restrictions may vary between and among series of Preferred Stock
in any and all respects so long as all shares of the same series of identical in
all respects, except that shares of any such series issued at different times
may have different dates from which dividends thereon cumulate. The authority of
the Board of Directors of the Corporation (or a duly authorized committee
thereof) with respect to each series shall include, but shall not be limited to,
the authority to determine the following:
 
        (a) The designation of such series;
 
        (b) The number of shares initially constituting such series;
 
        (c) The rate or rates and the time at which dividends on the shares of
    such series shall be paid, the periods in respect of which dividends are
    payable, the conditions upon such dividends, the relationship and
    preferences, if any, of such dividends to dividends payable on any other
    class or series of shares, whether or not such dividends shall be
    cumulative, partially cumulative or noncumulative, if such dividends shall
    be cumulative or partially cumulative, the date or dates from and after
    which, and the amounts in which, they shall accumulate, whether such
    dividends shall be share dividends, cash or other dividends or any
    combination thereof, and if such dividends shall include share dividends,
    whether such share dividends shall be payable in shares of the same or any
    other class or series of shares of the Corporation (whether now or hereafter
    authorized), or any combination thereof and the other terms and conditions,
    if any, applicable to dividends on shares of such series;
 
        (d) Whether or not the shares of such series shall be redeemable or
    subject to repurchase at the option of the Corporation or the holder thereof
    or upon the happening of a specified event, if such shares shall be
    redeemable, the terms and conditions or such redemption, including but not
    limited to the date or dates upon or after which such shares shall be
    redeemable, the amount per share which shall be payable upon such
    redemption, which amount may vary under different conditions and at
    different redemption dates and whether such amount shall be payable in cash,
    property or rights, including securities of the Corporation or another
    corporation;
 
        (e) The rights of the holders of shares of such series (which may vary
    depending upon the circumstances or nature of such liquidation, dissolution
    or winding up) in the event of the voluntary or involuntary liquidation,
    dissolution or winding up of the Corporation and the relationship or
    preference, if any, of such rights to rights of holders of stock of any
    other class or series. A liquidation, dissolution or winding up of the
    Corporation, as such terms are used in this subparagraph (e), shall not be
    deemed to be occasioned by or to include any merger of the Corporation with
    or into one or more corporations or other entities, any acquisition or
    exchange of the outstanding shares of one or more classes or series of the
    Corporation or any sale, lease, exchange or other disposition of all or a
    part of the assets of the Corporation.
 
        (f) Whether or not the shares of such series shall having voting powers
    and, if such shares shall have such voting powers, the terms and condition
    thereof, including, but not limited to, the right of the holders of such
    shares to vote as a separate class either alone or with the holders of
    shares of one or more other classes or series of stock and the right to have
    more (or less) than one vote per shares;
 
                                      2
<PAGE>
        (g) Whether or not a sinking fund shall be provided for the redemption
    of the shares of such series and, if such a sinking fund shall be provided,
    the terms and conditions thereof;
 
        (h) Whether or not a purchase fund shall be provided for the shares of
    such series and, if such a purchase fund shall be provided, the terms and
    conditions thereof;
 
        (i) Whether or not the shares of such series, at the option of either
    the Corporation or the holder or upon the happening of a specified event,
    shall be convertible into stock of any other class or series and, if such
    shares shall be so convertible, the terms and conditions of conversion,
    including, but not limited to, any provision for the adjustment of the
    conversion rate or the conversion price;
 
        (j) Whether or not the shares of such series, at the option of either
    the Corporation or the holder or upon the happening of a specified event,
    shall be exchangeable for securities, indebtedness or property of the
    Corporation and, if such shares shall be so exchangeable, the terms and
    conditions of exchange, including, but not limited to, any provision for the
    adjustment of the exchange rate or the exchange price; and
 
        (k) Any other preferences, limitations and relative rights as shall not
    be inconsistent with the provisions of this Article Fourth or the
    limitations provided by law.
 
    2. Except as otherwise provided herein, as required by law or in any
resolution of the Board of Directors (or a duly authorized committee thereof)
creating any series of Preferred Stock, the holders of shares of Preferred Stock
and all series thereof who are entitled to vote shall vote together with the
holders of shares of Common Stock, and not separately by class.
 
    FIFTH: The name of the incorporator is Elizabeth S. Schue and her mailing
address is c/o Vinson & Elkins, 2001 Ross Avenue, Suite 3700, Dallas, Texas
75201.
 
    SIXTH: The number of directors constituting the initial Board of Directors
is two (2), and the name of each person who is to serve as director until the
first annual meeting of stockholders or until his successor is elected and
qualified is John K. Carlyle and Donald J. Larson. The mailing address of each
of John K. Carlyle is 3010 LBJ Freeway, Suite 400, Dallas, Texas 75234, and the
mailing address of Donald J. Larson is 312 Union Wharf, Boston, Massachusetts
02109.
 
    SEVENTH: Directors of the Corporation need not be elected by written ballot
unless the bylaws of the Corporation otherwise provide.
 
    EIGHTH: In furtherance of, and not in limitation of, the powers conferred by
statute, the Board of Directors is expressly authorized to adopt, amend or
repeal the bylaws of the corporation.
 
    NINTH: Whenever a compromise or arrangement is proposed between the
corporation and its creditors or any class of them and/or between the
corporation and its stockholders or any class of them, any court of equitable
jurisdiction within the State of Delaware may, on the application in a summary
way of the corporation or of any creditor or stockholder thereof or on the
application of any receiver or receivers appointed for the corporation under the
provisions of Section 291 of Title 8 of the Delaware Code or on the application
of trustees in dissolution or of any receiver or receivers appointed for the
corporation under the provisions of Section 279 of Title 8 of the Delaware Code
order a meeting of the creditors or class of creditors, and/or of the
stockholders or class of stockholders of the corporation, as the case may be, to
be summoned in such manner as the said court directs. If a majority in number
representing three-fourths in value of the creditors or class of creditors,
and/or of the stockholders or class of stockholders of the corporation, as the
case may be, agree to any compromise or arrangement and to any reorganization of
the corporation as a consequence of such compromise or arrangement, the said
compromise or arrangement and the said reorganization shall, if sanctioned by
the court to which the said application has been made, be binding on all the
creditors or class of creditors, and/or on all the stockholders or class of
stockholders, of the corporation, as the case may be, and also on the
corporation.
 
                                      3
<PAGE>
    TENTH: No contract or transaction between the Corporation and one or more of
its directors, officers, or stockholders or between the Corporation and any
person (as used herein "person" means other corporation, partnership,
association, firm, trust, joint venture, political subdivision, or
instrumentality) or other organization in which one or more of the directors,
officers, or stockholders of the Corporation are directors, officers, or
stockholders, or have a financial interest, shall be void or voidable solely for
this reason, or solely because the director or officer is present at or
participates in the meeting of the board or committee which authorizes the
contract or transaction, or solely because his, her, or their votes are counted
for such purpose, if: (1) the material facts as to his or her relationship or
interest and as to the contract or transaction are disclosed or are known to the
board of directors or the committee, and the board of directors or committee in
good faith authorizes the contract or transaction by the affirmative votes of a
majority of the disinterested directors, even though the disinterested directors
be less than a quorum; or (2) the material facts as to his or her relationship
or interest and as to the contract or transaction are disclosed or are known to
the stockholders entitled to vote thereon, and the contract or transaction is
specifically approved in good faith by vote of the stockholders; or (3) the
contract or transaction is fair as to the Corporation as of the time it is
authorized, approved, or ratified by the board of directors, a committee
thereof, or the stockholders. Common or interested directors may be counted in
determining the presence of a quorum at a meeting of the board of directors or
of a committee which authorizes the contract or transaction.
 
    ELEVENTH: No director of the corporation shall be liable to the corporation
or its stockholders for monetary damages for breach of fiduciary duty as a
director, except for liability (i) for any breach of the director's duty of
loyalty to the corporation or its stockholders, (ii) for acts or omissions not
in good faith or which involve intentional misconduct or a knowing violation of
law, (iii) under Section 174 of the Delaware General Corporation Law, or (iv)
for any transaction from which the director derived an improper personal
benefit. In addition to the circumstances in which a director of the corporation
is not personally liable as set forth in the preceding sentence, a director of
the corporation shall not be liable to the fullest extent permitted by any
amendment to the Delaware General Corporation Law hereafter enacted that further
limits the liability of a director.
 
    TWELFTH: The corporation shall have the right, subject to any express
provisions or restrictions contained in this Certificate of Incorporation or
bylaws of the corporation, from time to time, to amend this certificate of
incorporation or any provision hereof in any manner now or hereafter provided by
law, and all rights and powers of any kind conferred upon a director or
stockholder of this corporation by this Certificate of Incorporation or any
amendment hereof are subject to such right of the Corporation.
 
    I, the undersigned, being the incorporator hereinbefore named, for the
purpose of forming a corporation pursuant to the Delaware General Corporation
Law, do make this certificate, hereby declaring that this is my act and deed and
that the facts herein stated are true, and accordingly have hereunto set my hand
this 21st day of April, 1997.


                                       /s/ Elizabeth S. Schue
                                       --------------------------------------
                                       Elizabeth S. Schue
 
                                      4
<PAGE>
                                                           EXHIBIT 3.2

                                     BYLAWS
                                       OF
                          CONCENTRA MANAGED CARE, INC.
 
                                   ARTICLE I
 
                                    OFFICES
 
    SECTION 1. REGISTERED OFFICE. The registered office of the Corporation
required by the General Corporation Law of the State of Delaware to be
maintained in the State of Delaware, shall be the registered office named in the
original Certificate of Incorporation of the Corporation (as the same may be
amended and restated from time to time, the "Certificate of Incorporation"), or
such other office as may be designated from time to time by the Board of
Directors in the manner provided by law. Should the Corporation maintain a
principal office within the State of Delaware such registered office need not be
identical to such principal office of the Corporation.
 
    SECTION 2. OTHER OFFICES. The Corporation may also have offices at such
other places both within and without the State of Delaware as the Board of
Directors may from time to time determine or the business of the Corporation may
require.
 
                                   ARTICLE II
 
                                  STOCKHOLDERS
 
    SECTION 1. PLACE OF MEETINGS. All meetings of the stockholders shall be held
at the principal office of the Corporation, or at such other place within or
without the State of Delaware as shall be specified or fixed in the notices or
waivers of notice thereof.
 
    SECTION 2. QUORUM; ADJOURNMENT OF MEETINGS. Unless otherwise required by law
or provided in the Certificate of Incorporation or these bylaws, the holders of
a majority of the stock issued and outstanding and entitled to vote thereat,
present in person or represented by proxy, shall constitute a quorum at any
meeting of stockholders for the transaction of business and the act of a
majority of such stock so represented at any meeting of stockholders at which a
quorum is present shall constitute the act of the meeting of stockholders. The
stockholders present at a duly organized meeting may continue to transact
business until adjournment, notwithstanding the withdrawal of enough
stockholders to leave less than a quorum.
 
    Notwithstanding the other provisions of the Certificate of Incorporation or
these bylaws, the chairman of the meeting or the holders of a majority of the
issued and outstanding stock, present in person or represented by proxy, at any
meeting of stockholders, whether or not a quorum is present, shall have the
power to adjourn such meeting from time to time, without any notice other than
announcement at the meeting of the time and place of the holding of the
adjourned meeting;
 
    PROVIDED, HOWEVER, if the adjournment is for more than thirty (30) days, or
if after the adjournment a new record date is fixed for the adjourned meeting, a
notice of the adjourned meeting shall be given to each stockholder of record
entitled to vote at such meeting. At any such adjourned meeting at which a
quorum shall be present or represented any business may be transacted which
might have been transacted at the meeting as originally called.
 
    SECTION 3. ANNUAL MEETINGS. An annual meeting of the stockholders, for the
election of directors to succeed those whose terms expire and for the
transaction of such other business as may properly come before the meeting,
shall be held at such place, within or without the State of Delaware, on such
date, and
 
                                      1
<PAGE>
at such time as the Board of Directors shall fix and set forth in the notice of
the meeting, which date shall be within thirteen (13) months subsequent to the
later of the date of incorporation or the last annual meeting of stockholders.
 
    SECTION 4. SPECIAL MEETINGS. Unless otherwise provided in the Certificate of
Incorporation, special meetings of the stockholders for any purpose or purposes
may be called at any time by the Chairman of the Board (if any), by the
President or by a majority of the Board of Directors, or by a majority of the
executive committee (if any), and shall be called by the Chairman of the Board
(if any), by the President or the Secretary upon the written request therefor,
stating the purpose or purposes of the meeting, delivered to such officer,
signed by the holder(s) of at least ten percent (l0%) of the issued and
outstanding stock entitled to vote at such meeting.
 
    SECTION 5. RECORD DATE. For the purpose of determining stockholders entitled
to notice of or to vote at any meeting of stockholders, or any adjournment
thereof, or entitled to express consent to corporate action in writing without a
meeting, or entitled to receive payment of any dividend or other distribution or
allotment of any rights, or entitled to exercise any rights in respect of any
change, conversion or exchange of stock or for the purpose of any other lawful
action, the Board of Directors of the Corporation may fix, in advance, a date as
the record date for any such determination of stockholders, which date shall not
be more than sixty (60) days nor less than ten (l0) days before the date of such
meeting, nor more than sixty (60) days prior to any other action.
 
    If the Board of Directors does not fix a record date for any meeting of the
stockholders, the record date for determining stockholders entitled to notice of
or to vote at such meeting shall be at the close of business on the day next
preceding the day on which notice is given, or, if in accordance with Article
VIII, Section 3 of these bylaws notice is waived, at the close of business on
the day next preceding the day on which the meeting is held. If, in accordance
with Section 12 of this Article II, corporate action without a meeting of
stockholders is to be taken, the record date for determining stockholders
entitled to express consent to such corporate action in writing, when no prior
action by the Board of Directors is necessary, shall be the day on which the
first written consent is expressed. The record date for determining stockholders
for any other purpose shall be at the close of business on the day on which the
Board of Directors adopts the resolution relating thereto.
 
    A determination of stockholders of record entitled to notice of or to vote
at a meeting of stockholders shall apply to any adjournment of the meeting;
provided, however, that the Board of Directors may fix a new record date for the
adjourned meeting.
 
    SECTION 6. NOTICE OF MEETINGS. Written notice of the place, date and hour of
all meetings, and, in case of a special meeting, the purpose or purposes for
which the meeting is called, shall be given by or at the direction of the
Chairman of the Board (if any) or the President, the Secretary or the other
person(s) calling the meeting to each stockholder entitled to vote thereat not
less than ten (10) nor more than sixty (60) days before the date of the meeting.
Such notice may be delivered either personally or by mail. If mailed, notice is
given when deposited in the United States mail, postage prepaid, directed to the
stockholder at his address as it appears on the records of the Corporation.
 
    SECTION 7. STOCK LIST. A complete list of stockholders entitled to vote at
any meeting of stockholders, arranged in alphabetical order for each class of
stock and showing the address of each such stockholder and the number of shares
registered in the name of such stockholder, shall be open to the examination of
any stockholder, for any purpose germane to the meeting, during ordinary
business hours, for a period of at least ten (10) days prior to the meeting,
either at a place within the city where the meeting is to be held, which place
shall be specified in the notice of the meeting, or if not so specified, at the
place where the meeting is to be held. The stock list shall also be produced and
kept at the time and place of the meeting during the whole time thereof, and may
be inspected by any stockholder who is present.
 
                                      2
<PAGE>
    SECTION 8. PROXIES. Each stockholder entitled to vote at a meeting of
stockholders or to express consent or dissent to a corporate action in writing
without a meeting may authorize another person or persons to act for him by
proxy. Proxies for use at any meeting of stockholders shall be filed with the
Secretary, or such other officer as the Board of Directors may from time to time
determine by resolution, before or at the time of the meeting. All proxies shall
be received and taken charge of and all ballots shall be received and canvassed
by the secretary of the meeting who shall decide all questions touching upon the
qualification of voters, the validity of the proxies, and the acceptance or
rejection of votes, unless an inspector or inspectors shall have been appointed
by the chairman of the meeting, in which event such inspector or inspectors
shall decide all such questions.
 
    No proxy shall be valid after three (3) years from its date, unless the
proxy provides for a longer period. Each proxy shall be revocable unless
expressly provided therein to be irrevocable and coupled with an interest
sufficient in law to support an irrevocable power.
 
    Should a proxy designate two or more persons to act as proxies, unless such
instrument shall provide the contrary, a majority of such persons present at any
meeting at which their powers thereunder are to be exercised shall have and may
exercise all the powers of voting or giving consents thereby conferred, or if
only one be present, then such powers may be exercised by that one; or, if an
even number attend and a majority do not agree on any particular issue, each
proxy so attending shall be entitled to exercise such powers in respect of the
same portion of the shares as he is of the proxies representing such shares.
 
    SECTION 9. VOTING; ELECTIONS; INSPECTORS. Unless otherwise required by law
or provided in the Certificate of Incorporation, each stockholder shall have one
vote for each share of stock entitled to vote which is registered in his name on
the record date for the meeting. Shares registered in the name of another
corporation, domestic or foreign, may be voted by such officer, agent or proxy
as the bylaw (or comparable instrument) of such corporation may prescribe, or in
the absence of such provision, as the Board of Directors (or comparable body) of
such corporation may determine. Shares registered in the name of a deceased
person may be voted by his executor or administrator, either in person or by
proxy.
 
    All voting, except as required by the Certificate of Incorporation or where
otherwise required by law, may be by a voice vote; provided, however, that upon
demand therefor by stockholders holding a majority of the issued and outstanding
stock present in person or by proxy at any meeting a stock vote shall be taken.
Every stock vote shall be taken by written ballots, each of which shall state
the name of the stockholder or proxy voting and such other information as may be
required under the procedure established for the meeting. All elections of
directors shall be by ballot, unless otherwise provided in the Certificate of
Incorporation.
 
    At any meeting at which a vote is taken by ballots, the chairman of the
meeting may appoint one or more inspectors, each of whom shall subscribe an oath
or affirmation to execute faithfully the duties of inspector at such meeting
with strict impartiality and according to the best of his ability. Such
inspector shall receive the ballots, count the votes and make and sign a
certificate of the result thereof. The chairman of the meeting may appoint any
person to serve as inspector, except no candidate for the office of director
shall be appointed as an inspector.
 
    Unless otherwise provided in the Certificate of Incorporation, cumulative
voting for the election of directors shall be prohibited.
 
    SECTION 10. CONDUCT OF MEETINGS. The meetings of the stockholders shall be
presided over by the Chairman of the Board (if any), or if he is not present, by
the President, or if neither the Chairman of the Board (if any), nor President
is present, by a chairman elected at the meeting. The Secretary of the
Corporation, if present, shall act as secretary of such meetings, or if he is
not present, an Assistant Secretary shall so act; if neither the Secretary nor
an Assistant Secretary is present, then a secretary shall be appointed by the
chairman of the meeting. The chairman of any meeting of stockholders shall
determine the order of business and the procedure at the meeting, including such
regulation of the manner
 
                                      3
<PAGE>
of voting and the conduct of discussion as seem to him in order. Unless the
chairman of the meeting of stockholders shall otherwise determine, the order of
business shall be as follows:
 
    (a) Calling of meeting to order.
 
    (b) Election of a chairman and the appointment of a secretary if necessary.
 
    (c) Presentation of proof of the due calling of the meeting.
 
    (d) Presentation and examination of proxies and determination of a quorum.
 
    (e) Reading and settlement of the minutes of the previous meeting.
 
    (f) Reports of officers and committees.
 
    (g) The election of directors if an annual meeting, or a meeting called for
that purpose.
 
    (h) Unfinished business.
 
    (i) New business.
 
    (j) Adjournment.
 
    SECTION 11. TREASURY STOCK. The Corporation shall not vote, directly or
indirectly, shares of its own stock owned by it and such shares shall not be
counted for quorum purposes.
 
    SECTION 12. ACTION WITHOUT MEETING. Unless otherwise provided in the
Certificate of Incorporation, any action permitted or required by law, the
Certificate of Incorporation or these bylaws to be taken at a meeting of
stockholders, may be taken without a meeting, without prior notice and without a
vote, if a consent in writing, setting forth the action so taken, shall be
signed by the holders of outstanding stock having not less than the minimum
number of votes that would be necessary to authorize or take such action at a
meeting at which all shares entitled to vote thereon were present and voted.
Prompt notice of the taking of the corporate action without a meeting by less
than a unanimous written consent shall be given by the Secretary to those
stockholders who have not consented in writing.
 
                                  ARTICLE III
                               BOARD OF DIRECTORS
 
    SECTION 1. POWER; NUMBER; TERM OF OFFICE. The business and affairs of the
Corporation shall be managed by or under the direction of the Board of
Directors, and subject to the restrictions imposed by law or the Certificate of
Incorporation, they may exercise all the powers of the Corporation.
 
    The number of directors of the Corporation shall be determined from time to
time by resolution of the Board of Directors, unless the Certificate of
Incorporation fixes the number of directors, in which case a change in the
number of directors shall be made only by amendment of the Certificate of
Incorporation. Each director shall hold office for the term for which he is
elected, and until his successor shall have been elected and qualified or until
his earlier death, resignation or removal.
 
    Unless otherwise provided in the Certificate of Incorporation, directors
need not be stockholders nor residents of the State of Delaware.
 
    SECTION 2. QUORUM. Unless otherwise provided in the Certificate of
Incorporation, a majority of the total number of directors shall constitute a
quorum for the transaction of business of the Board of Directors and the vote of
a majority of the directors present at a meeting at which a quorum is present
shall be the act of the Board of Directors.
 
                                      4
<PAGE>
    SECTION 3. PLACE OF MEETINGS; ORDER OF BUSINESS. The directors may hold
their meetings and may have an office and keep the books of the Corporation,
except as otherwise provided by law, in such place or places, within or without
the State of Delaware, as the Board of Directors may from time to time determine
by resolution. At all meetings of the Board of Directors business shall be
transacted in such order as shall from time to time be determined by the
Chairman of the Board (if any), or in his absence by the President, or by
resolution of the Board of Directors.
 
    SECTION 4. FIRST MEETING. Each newly elected Board of Directors may hold its
first meeting for the purpose of organization and the transaction of business,
if a quorum is present, immediately after and at the same place as the annual
meeting of the stockholders. Notice of such meeting shall not be required. At
the first meeting of the Board of Directors in each year at which a quorum shall
be present, held next after the annual meeting of stockholders, the Board of
Directors shall proceed to the election of the officers of the Corporation.
 
    SECTION 5. REGULAR MEETINGS. Regular meetings of the Board of Directors
shall be held at such times and places as shall be designated from time to time
by resolution of the Board of Directors. Notice of such regular meetings shall
not be required.
 
    SECTION 6. SPECIAL MEETINGS. Special meetings of the Board of Directors may
be called by the Chairman of the Board (if any), the President or, on the
written request of any two directors, by the Secretary, in each case on at least
twenty-four (24) hours personal, written, telegraphic, cable or wireless notice
to each director. Such notice, or any waiver thereof pursuant to Article VIII,
Section 3 hereof, need not state the purpose or purposes of such meeting, except
as may otherwise be required by law or provided for in the Certificate of
Incorporation or these bylaws.
 
    SECTION 7. REMOVAL. Any director or the entire Board of Directors may be
removed, with or without cause, by the holders of a majority of the shares then
entitled to vote at an election of directors; provided that, unless the
Certificate of Incorporation otherwise provides, if the Board of Directors is
classified, then the stockholders may effect such removal only for cause; and
provided further that, if the Certificate of Incorporation expressly grants to
stockholders the right to cumulate votes for the election of directors and if
less than the entire board is to be removed, no director may be removed without
cause if the votes cast against his removal would be sufficient to elect him if
then cumulatively voted at an election of the entire Board of Directors, or, if
there be classes of directors, at an election of the class of directors of which
such director is a part.
 
    SECTION 8. VACANCIES; INCREASES IN THE NUMBER OF DIRECTORS. Unless otherwise
provided in the Certificate of Incorporation, vacancies and newly created
directorships resulting from any increase in the authorized number of directors
may be filled by a majority of the directors then in office, although less than
a quorum, or a sole remaining director; and any director so chosen shall hold
office until the next annual election and until his successor shall be duly
elected and shall qualify, unless sooner displaced.
 
    If the directors of the Corporation are divided into classes, any directors
elected to fill vacancies or newly created directorships shall hold office until
the next election of the class for which such directors shall have been chosen,
and until their successors shall be duly elected and shall qualify.
 
    SECTION 9. COMPENSATION. Unless otherwise restricted by the Certificate of
Incorporation, the Board of Directors shall have the authority to fix the
compensation of directors.
 
    SECTION 10. ACTION WITHOUT A MEETING; TELEPHONE CONFERENCE MEETING. Unless
otherwise restricted by the Certificate of Incorporation, any action required or
permitted to be taken at any meeting of the Board of Directors, or any committee
designated by the Board of Directors, may be taken without a meeting if all
members of the Board of Directors or committee, as the case may be consent
thereto in writing, and the writing or writings are filed with the minutes of
proceedings of the Board of Directors or committee. Such
 
                                      5
<PAGE>
consent shall have the same force and effect as a unanimous vote at a meeting,
and may be stated as such in any document or instrument filed with the Secretary
of State of Delaware.
 
    Unless otherwise restricted by the Certificate of Incorporation, subject to
the requirement for notice of meetings, members of the Board of Directors, or
members of any committee designated by the Board of Directors, may participate
in a meeting of such Board of Directors or committee, as the case may be, by
means of a conference telephone or similar communications equipment by means of
which all persons participating in the meeting can hear each other, and
participation in such a meeting shall constitute presence in person at such
meeting, except where a person participates in the meeting for the express
purpose of objecting to the transaction of any business on the ground that the
meeting is not lawfully called or convened.
 
    SECTION 11. APPROVAL OR RATIFICATION OF ACTS OR CONTRACTS BY
STOCKHOLDERS. The Board of Directors in its discretion may submit any act or
contract for approval or ratification at any annual meeting of the stockholders,
or at any special meeting of the stockholders called for the purpose of
considering any such act or contract, and any act or contract that shall be
approved or be ratified by the vote of the stockholders holding a majority of
the issued and outstanding shares of stock of the Corporation entitled to vote
and present in person or by proxy at such meeting (provided that a quorum is
present), shall be as valid and as binding upon the Corporation and upon all the
stockholders as if it has been approved or ratified by every stockholder of the
Corporation. In addition, any such act or contract may be approved or ratified
by the written consent of stockholders holding a majority of the issued and
outstanding shares of capital stock of the Corporation entitled to vote and such
consent shall be as valid and as binding upon the Corporation and upon all the
stockholders as if it had been approved or ratified by every stockholder of the
Corporation.
 
                                   ARTICLE IV
                                   COMMITTEES
 
    SECTION 1. DESIGNATION; POWERS. The Board of Directors may, by resolution
passed by a majority of the whole board, designate one or more committees,
including, if they shall so determine, an executive committee, each such
committee to consist of one or more of the directors of the Corporation. Any
such designated committee shall have and may exercise such of the powers and
authority of the Board of Directors in the management of the business and
affairs of the Corporation as may be provided in such resolution, except that no
such committee shall have the power or authority of the Board of Directors in
reference to amending the Certificate of Incorporation, adopting an agreement of
merger or consolidation, recommending to the stockholders the sale, lease or
exchange of all or substantially all of the Corporation's property and assets,
recommending to the stockholders a dissolution of the Corporation or a
revocation of a dissolution of the Corporation, or amending, altering or
repealing the bylaws or adopting new bylaws for the Corporation and, unless such
resolution or the Certificate of Incorporation expressly so provides, no such
committee shall have the power or authority to declare a dividend or to
authorize the issuance of stock. Any such designated committee may authorize the
seal of the Corporation to be affixed to all papers which may require it. In
addition to the above such committee or committees shall have such other powers
and limitations of authority as may be determined from time to time by
resolution adopted by the Board of Directors.
 
    SECTION 2. PROCEDURE; MEETINGS; QUORUM. Any committee designated pursuant to
Section 1 of this Article shall choose its own chairman, shall keep regular
minutes of its proceedings and report the same to the Board of Directors when
requested, shall fix its own rules or procedures, and shall meet at such times
and at such place or places as may be provided by such rules, or by resolution
of such committee or resolution of the Board of Directors. At every meeting of
any such committee, the presence of a majority
 
                                      6
<PAGE>
of all the members thereof shall constitute a quorum and the affirmative vote of
a majority of the members present shall be necessary for the adoption by it of
any resolution.
 
    SECTION 3. SUBSTITUTION OF MEMBERS. The Board of Directors may designate one
or more directors as alternate members of any committee, who may replace any
absent or disqualified member at any meeting of such committee. In the absence
or disqualification of a member of a committee, the member or members present at
any meeting and not disqualified from voting, whether or not constituting a
quorum, may unanimously appoint another member of the Board of Directors to act
at the meeting in the place of the absent or disqualified member.
 
                                   ARTICLE V
                                    OFFICERS
 
    SECTION 1. NUMBER, TITLES AND TERM OF OFFICE. The officers of the
Corporation shall be a President, one or more Vice Presidents (any one or more
of whom may be designated Executive Vice President or Senior Vice President), a
Treasurer, a Secretary and, if the Board of Directors so elects, a Chairman of
the Board and such other officers as the Board of Directors may from time to
time elect or appoint. Each officer shall hold office until his successor shall
be duly elected and shall qualify or until his death or until he shall resign or
shall have been removed in the manner hereinafter provided. Any number of
offices may be held by the same person, unless the Certificate of Incorporation
provides otherwise. Except for the Chairman of the Board, if any, no officer
need be a director.
 
    SECTION 2. SALARIES. The salaries or other compensation of the officers and
agents of the Corporation shall be fixed from time to time by the Board of
Directors.
 
    SECTION 3. REMOVAL. Any officer or agent elected or appointed by the Board
of Directors may be removed, either with or without cause, by the vote of a
majority of the whole Board of Directors at a special meeting called for the
purpose, or at any regular meeting of the Board of Directors, provided the
notice for such meeting shall specify that the matter of any such proposed
removal will be considered at the meeting but such removal shall be without
prejudice to the contract rights, if any, of the person so removed. Election or
appointment of an officer or agent shall not of itself create contract rights.
 
    SECTION 4. VACANCIES. Any vacancy occurring in any office of the Corporation
may be filled by the Board of Directors.
 
    SECTION 5. POWERS AND DUTIES OF THE CHIEF EXECUTIVE OFFICER. The President
shall be the chief executive officer of the Corporation unless the Board of
Directors otherwise unanimously designates the Chairman of the Board as chief
executive officer. Subject to the control of the Board of Directors and the
executive committee (if any), the chief executive officer shall have general
executive charge, management and control of the properties, business and
operations of the Corporation with all such powers as may be reasonably incident
to such responsibilities; he may agree upon and execute all leases, contracts,
evidences of indebtedness and other obligations in the name of the Corporation
and may sign all certificates for shares of capital stock of the Corporation;
and shall have such other powers and duties as designated in accordance with
these bylaws and as from time to time may be assigned to him by the Board of
Directors.
 
    SECTION 6. POWERS AND DUTIES OF THE CHAIRMAN OF THE BOARD. If elected, the
Chairman of the Board shall preside at all meetings of the stockholders and of
the Board of Directors; and he shall have such other powers and duties as
designated in these bylaws and as from time to time may be assigned to him by
the Board of Directors.
 
                                      7
<PAGE>
    SECTION 7. POWERS AND DUTIES OF THE PRESIDENT. Unless the Board of Directors
otherwise determines, the President shall have the authority to agree upon and
execute all leases, contracts, evidences of indebtedness and other obligations
in the name of the Corporation; and, unless the Board of Directors otherwise
determines, he shall, in the absence of the Chairman of the Board or if there be
no Chairman of the Board, preside at all meetings of the stockholders and
(should he be a director) of the Board of Directors; and he shall have such
other powers and duties as designated in accordance with these bylaws and as
from time to time may be assigned to him by the Board of Directors.
 
    SECTION 8. VICE PRESIDENTS. In the absence of the President, or in the event
of his inability or refusal to act, a Vice President designated by the Board of
Directors shall perform the duties of the President, and when so acting shall
have all the powers of and be subject to all the restrictions upon the
President. In the absence of a designation by the Board of Directors of a Vice
President to perform the duties of the President, or in the event of his absence
or inability or refusal to act, the Vice President who is present and who is
senior in terms of time as a Vice President of the Corporation shall so act. The
Vice Presidents shall perform such other duties and have such other powers as
the Board of Directors may from time to time prescribe.
 
    SECTION 9. TREASURER. The Treasurer shall have responsibility for the
custody and control of all the funds and securities of the Corporation, and he
shall have such other powers and duties as designated in these bylaws and as
from time to time may be assigned to him by the Board of Directors. He shall
perform all acts incident to the position of Treasurer, subject to the control
of the chief executive officer and the Board of Directors; and he shall, if
required by the Board of Directors, give such bond for the faithful discharge of
his duties in such form as the Board of Directors may require.
 
    SECTION 10. ASSISTANT TREASURERS. Each Assistant Treasurer shall have the
usual powers and duties pertaining to his office, together with such other
powers and duties as designated in these bylaws and as from time to time may be
assigned to him by the chief executive officer or the Board of Directors. The
Assistant Treasurers shall exercise the powers of the Treasurer during that
officer's absence or inability or refusal to act.
 
    SECTION 11. SECRETARY. The Secretary shall keep the minutes of all meetings
of the Board of Directors, committees of directors and the stockholders, in
books provided for that purpose; he shall attend to the giving and serving of
all notices; he may in the name of the Corporation affix the seal of the
Corporation to all contracts of the Corporation and attest the affixation of the
seal of the Corporation thereto; he may sign with the other appointed officers
all certificates for shares of capital stock of the Corporation; he shall have
charge of the certificate books, transfer books and stock ledgers, and such
other books and papers as the Board of Directors may direct, all of which shall
at all reasonable times be open to inspection of any director upon application
at the office of the Corporation during business hours; he shall have such other
powers and duties as designated in these bylaws and as from time to time may be
assigned to him by the Board of Directors; and he shall in general perform all
acts incident to the office of Secretary, subject to the control of the chief
executive officer and the Board of Directors.
 
    SECTION 12. ASSISTANT SECRETARIES. Each Assistant Secretary shall have the
usual powers and duties pertaining to his office, together with such other
powers and duties as designated in these bylaws and as from time to time may be
assigned to him by the chief executive officer or the Board of Directors. The
Assistant Secretaries shall exercise the powers of the Secretary during that
officer's absence or inability or refusal to act.
 
    SECTION 13. ACTION WITH RESPECT TO SECURITIES OF OTHER CORPORATIONS. Unless
otherwise directed by the Board of Directors, the chief executive officer shall
have power to vote and otherwise act on behalf of the Corporation, in person or
by proxy, at any meeting of security holders of or with respect to any action of
security holders of any other corporation in which this Corporation may hold
securities and otherwise to
 
                                      8
<PAGE>
exercise any and all rights and powers which this Corporation may possess by
reason of its ownership of securities in such other corporation.
 
                                   ARTICLE VI
                         INDEMNIFICATION OF DIRECTORS,
                         OFFICERS, EMPLOYEES AND AGENTS
 
    SECTION 1. RIGHT TO INDEMNIFICATION. Each person who was or is made a party
or is threatened to be made a party to or is involved in any action, suit or
proceeding, whether civil, criminal, administrative or investigative
(hereinafter a "proceeding"), by reason of the fact that he or she or a person
of whom he or she is the legal representative, is or was or has agreed to become
a director or officer of the Corporation or is or was serving or has agreed to
serve at the request of the Corporation as a director, officer, employee or
agent of another corporation or of a partnership, joint venture, trust or other
enterprise, including service with respect to employee benefit plans, whether
the basis of such proceeding is alleged action in an official capacity as a
director or officer or in any other capacity while serving or having agreed to
serve as a director or officer, shall be indemnified and held harmless by the
Corporation to the fullest extent authorized by the Delaware General Corporation
Law, as the same exists or may hereafter be amended, (but, in the case of any
such amendment, only to the extent that such amendment permits the Corporation
to provide broader indemnification rights than said law permitted the
Corporation to provide prior to such amendment) against all expense, liability
and loss (including without limitation, attorneys' fees, judgments, fines, ERISA
excise taxes or penalties and amounts paid or to be paid in settlement)
reasonably incurred or suffered by such person in connection therewith and such
indemnification shall continue as to a person who has ceased to serve in the
capacity which initially entitled such person to indemnity hereunder and shall
inure to the benefit of his or her heirs, executors and administrators;
PROVIDED, HOWEVER, that the Corporation shall indemnify any such person seeking
indemnification in connection with a proceeding (or part thereof), other than a
proceeding (or part thereof) brought under Section 3 of this Article VI,
initiated by such person or his or her heirs, executors and administrators only
if such proceeding (or part thereof) was authorized by the board of directors of
the Corporation. The right to indemnification conferred in this Article VI shall
be a contract right and shall include the right to be paid by the Corporation
the expenses incurred in defending any such proceeding in advance of its final
disposition; PROVIDED, HOWEVER, that, if the Delaware General Corporation Law
requires, the payment of such expenses incurred by a current, former or proposed
director or officer in his or her capacity as a director or officer or proposed
director or officer (and not in any other capacity in which service was or is or
has been agreed to be rendered by such person while a director or officer,
including, without limitation, service to an employee benefit plan) in advance
of the final disposition of a proceeding, shall be made only upon delivery to
the Corporation of an undertaking, by or on behalf of such indemnified person,
to repay all amounts so advanced if it shall ultimately be determined that such
indemnified person is not entitled to be indemnified under this Section or
otherwise.
 
    SECTION 2. INDEMNIFICATION OF EMPLOYEES AND AGENTS. The Corporation may, by
action of its Board of Directors, provide indemnification to employees and
agents of the Corporation, individually or as a group, with the same scope and
effect as the indemnification of directors and officers provided for in this
Article.
 
    SECTION 3. RIGHT OF CLAIMANT TO BRING SUIT. If a written claim received by
the Corporation from or on behalf of an indemnified party under this Article VI
is not paid in full by the Corporation within ninety days after such receipt,
the claimant may at any time thereafter bring suit against the Corporation to
recover the unpaid amount of the claim and, if successful in whole or in part,
the claimant shall be entitled to be paid also the expense of prosecuting such
claim. It shall be a defense to any such action (other than an action brought to
enforce a claim for expenses incurred in defending any proceeding in advance of
its final disposition where the required undertaking, if any is required, has
been tendered to the Corporation)
 
                                      9
<PAGE>
that the claimant has not met the standards of conduct which make it permissible
under the Delaware General Corporation Law for the Corporation to indemnify the
claimant for the amount claimed, but the burden of proving such defense shall be
on the Corporation. Neither the failure of the Corporation (including its Board
of Directors, independent legal counsel, or its stockholders) to have made a
determination prior to the commencement of such action that indemnification of
the claimant is proper in the circumstances because he or she has met the
applicable standard of conduct set forth in the Delaware General Corporation
Law, nor an actual determination by the Corporation (including its Board of
Directors, independent legal counsel, or its stockholders) that the claimant has
not met such applicable standard of conduct, shall be a defense to the action or
create a presumption that the claimant has not met the applicable standard of
conduct.
 
    SECTION 4. NONEXCLUSIVITY OF RIGHTS. The right to indemnification and the
advancement and payment of expenses conferred in this Article VI shall not be
exclusive of any other right which any person may have or hereafter acquire
under any law (common or statutory), provision of the Certificate of
Incorporation of the Corporation, bylaw, agreement, vote of stockholders or
disinterested directors or otherwise.
 
    SECTION 5. INSURANCE. The Corporation may maintain insurance, at its
expense, to protect itself and any person who is or was serving as a director,
officer, employee or agent of the Corporation or is or was serving at the
request of the Corporation as a director, officer, employee or agent of another
corporation, partnership, joint venture, trust or other enterprise against any
expense, liability or loss, whether or not the Corporation would have the power
to indemnify such person against such expense, liability or loss under the
Delaware General Corporation Law.
 
    SECTION 6. SAVINGS CLAUSE. If this Article VI or any portion hereof shall be
invalidated on any ground by any court of competent jurisdiction, then the
Corporation shall nevertheless indemnify and hold harmless each director and
officer of the Corporation, as to costs, charges and expenses (including
attorneys' fees), judgments, fines, and amounts paid in settlement with respect
to any action, suit or proceeding, whether civil, criminal, administrative or
investigative to the full extent permitted by any applicable portion of this
Article VI that shall not have been invalidated and to the fullest extent
permitted by applicable law.
 
    SECTION 7. DEFINITIONS. For purposes of this Article, reference to the
"Corporation" shall include, in addition to the Corporation, any constituent
corporation (including any constituent of a constituent) absorbed in a
consolidation or merger prior to (or, in the case of an entity specifically
designated in a resolution of the Board of Directors, after) the adoption hereof
and which, if its separate existence had continued, would have had the power and
authority to indemnify its directors, officers and employees or agents, so that
any person who is or was a director, officer, employee or agent of such
constituent corporation, or is or was serving at the request of such constituent
corporation as a director, officer, employee or agent of another corporation,
partnership, joint venture, trust or other enterprise, shall stand in the same
position under the provisions of this Article with respect to the resulting or
surviving corporation as he would have with respect to such constituent
corporation if its separate existence had continued.
 
                                  ARTICLE VII
                                 CAPITAL STOCK
 
    SECTION 1. CERTIFICATES OF STOCK. The certificates for shares of the capital
stock of the Corporation shall be in such form, not inconsistent with that
required by law and the Certificate of Incorporation, as shall be approved by
the Board of Directors. The Chairman of the Board (if any), President or a Vice
President shall cause to be issued to each stockholder one or more certificates,
under the seal of the Corporation or a facsimile thereof if the Board of
Directors shall have provided for such seal, and signed
 
                                      10
<PAGE>
by the Chairman of the Board (if any), President or a Vice President and the
Secretary or an Assistant Secretary or the Treasurer or an Assistant Treasurer
certifying the number of shares (and, if the stock of the Corporation shall be
divided into classes or series, the class and series of such shares) owned by
such stockholder in the Corporation; provided, however, that any of or all the
signatures on the certificate may be facsimile. The stock record books and the
blank stock certificate books shall be kept by the Secretary, or at the office
of such transfer agent or transfer agents as the Board of Directors may from
time to time by resolution determine. In case any officer, transfer agent or
registrar who shall have signed or whose facsimile signature or signatures shall
have been placed upon any such certificate or certificates shall have ceased to
be such officer, transfer agent or registrar before such certificate is issued
by the Corporation, such certificate may nevertheless be issued by the
Corporation with the same effect as if such person were such officer, transfer
agent or registrar at the date of issue. The stock certificates shall be
consecutively numbered and shall be entered in the books of the Corporation as
they are issued and shall exhibit the holder's name and number of shares.
 
    SECTION 2. TRANSFER OF SHARES. The shares of stock of the Corporation shall
be transferable only on the books of the Corporation by the holders thereof in
person or by their duly authorized attorneys or legal representatives upon
surrender and cancellation of certificates for a like number of shares. Upon
surrender to the Corporation or a transfer agent of the Corporation of a
certificate for shares duly endorsed or accompanied by proper evidence of
succession, assignment or authority to transfer, it shall be the duty of the
Corporation to issue a new certificate to the person entitled thereto, cancel
the old certificate and record the transaction upon its books.
 
    SECTION 3. OWNERSHIP OF SHARES. The Corporation shall be entitled to treat
the holder of record of any share or shares of capital stock of the Corporation
as the holder in fact thereof and, accordingly, shall not be bound to recognize
any equitable or other claim to or interest in such share or shares on the part
of any other person, whether or not it shall have express or other notice
thereof, except as otherwise provided by the laws of the State of Delaware.
 
    SECTION 4. REGULATIONS REGARDING CERTIFICATES. The Board of Directors shall
have the power and authority to make all such rules and regulations as they may
deem expedient concerning the issue, transfer and registration or the
replacement of certificates for shares of capital stock of the Corporation.
 
    SECTION 5. LOST OR DESTROYED CERTIFICATES. The Board of Directors may
determine the conditions upon which a new certificate of stock may be issued in
place of a certificate which is alleged to have been lost, stolen or destroyed;
and may, in their discretion, require the owner of such certificate or his legal
representative to give bond, with sufficient surety, to indemnify the
Corporation and each transfer agent and registrar against any and all losses or
claims which may arise by reason of the issue of a new certificate in the place
of the one so lost, stolen or destroyed.
 
                                  ARTICLE VIII
                            MISCELLANEOUS PROVISIONS
 
    SECTION 1. FISCAL YEAR. The fiscal year of the Corporation shall be such as
established from time to time by the Board of Directors.
 
    SECTION 2. CORPORATE SEAL. The Board of Directors may provide a suitable
seal, containing the name of the Corporation. The Secretary shall have charge of
the seal (if any). If and when so directed by the Board of Directors or a
committee thereof, duplicates of the seal may be kept and used by the Treasurer
or by the Assistant Secretary or Assistant Treasurer.
 
    SECTION 3. NOTICE AND WAIVER OF NOTICE. Whenever any notice is required to
be given by law, the Certificate of Incorporation or under the provisions of
these bylaws, said notice shall be deemed to be
 
                                      11
<PAGE>
sufficient if given (i) by telegraphic, cable or wireless transmission or (ii)
by deposit of the same in a post office box in a sealed prepaid wrapper
addressed to the person entitled thereto at his post office address, as it
appears on the records of the Corporation, and such notice shall be deemed to
have been given on the day of such transmission or mailing, as the case may be.
 
    Whenever notice is required to be given by law, the Certificate of
Incorporation or under any of the provisions of these bylaws, a written waiver
thereof, signed by the person entitled to notice, whether before or after the
time stated therein, shall be deemed equivalent to notice. Attendance of a
person at a meeting shall constitute a waiver of notice of such meeting, except
when the person attends a meeting for the express purpose of objecting, at the
beginning of the meeting, to the transaction of any business because the meeting
is not lawfully called or convened. Neither the business to be transacted at,
nor the purpose of, any regular or special meeting of the stockholders,
directors, or members of a committee of directors need be specified in any
written waiver of notice unless so required by the Certificate of Incorporation
or the bylaws.
 
    SECTION 4. RESIGNATIONS. Any director, member of a committee or officer may
resign at any time. Such resignation shall be made in writing and shall take
effect at the time specified therein, or if no time be specified, at the time of
its receipt by the chief executive officer or Secretary. The acceptance of a
resignation shall not be necessary to make it effective, unless expressly so
provided in the resignation.
 
    SECTION 5. FACSIMILE SIGNATURES. In addition to the provisions for the use
of facsimile signatures elsewhere specifically authorized in these bylaws,
facsimile signatures of any officer or officers of the Corporation may be used
whenever and as authorized by the Board of Directors.
 
    SECTION 6. RELIANCE UPON BOOKS, REPORTS AND RECORDS. Each director and each
member of any committee designated by the Board of Directors shall, in the
performance of his duties, be fully protected in relying in good faith upon the
books of account or reports made to the Corporation by any of its officers, or
by an independent certified public accountant, or by an appraiser selected with
reasonable care by the Board of Directors or by any such committee, or in
relying in good faith upon other records of the Corporation.
 
                                   ARTICLE IX
                                   AMENDMENTS
 
    If provided in the Certificate of Incorporation of the Corporation, the
Board of Directors shall have the power to adopt, amend and repeal from time to
time bylaws of the Corporation, subject to the right of the stockholders
entitled to vote with respect thereto to amend or repeal such bylaws as adopted
or amended by the Board of Directors.
 
                                      12
<PAGE>


                             ARTHUR ANDERSEN LLP

                  CONSENT OF INDEPENDENT PUBLIC ACCOUNTANTS


As independent public accountants, we hereby consent to the use of our 
reports (and to all references to our Firm) included in or made part of this 
(the attached) prospectus.


                                            /s/ Arthur Andersen LLP
                                            -----------------------------
                                            ARTHUR ANDERSEN LLP

Boston, Massachsetts
May 13, 1997


<PAGE>


                  CONSENT OF INDEPENDENT PUBLIC ACCOUNTANTS


As independent public accountants, we hereby consent to the use of our 
reports (and to all references to our Firm) included in or made part of this 
registration statement.


                                            /s/ Arthur Andersen LLP
                                            -----------------------------
                                            ARTHUR ANDERSEN LLP

Dallas, Texas
May 13, 1997


<PAGE>


             

                                DIRECTOR'S CONSENT


     I hereby consent to being named as a Director of Concentra Managed Care, 
Inc. in the Joint Proxy Statement/Prospectus and any amendments thereto to 
which this consent has been filed as an exhibit.

Date:  May 12, 1997                         /s/ Robert W. O'Leary
                                            ----------------------------
                                            Robert W. O'Leary



<PAGE>


        

                                DIRECTOR'S CONSENT


     I hereby consent to being named as a Director of Concentra Managed Care, 
Inc. in the Joint Proxy Statement/Prospectus and any amendments thereto to 
which this consent has been filed as an exhibit.

Date:  May 12, 1997                         /s/ Robert A. Ortenzio
                                            ----------------------------
                                            Robert A. Ortenzio

<PAGE>




                                DIRECTOR'S CONSENT


     I hereby consent to being named as a Director of Concentra Managed Care, 
Inc. in the Joint Proxy Statement/Prospectus and any amendments thereto to 
which this consent has been filed as an exhibit.

Date:  May 12, 1997                         /s/ Paul B. Queally
                                            ----------------------------
                                            Paul B. Queally

<PAGE>


                                  DIRECTOR'S CONSENT


     I hereby consent to being named as a Director of Concentra Managed Care, 
Inc. in the Joint Proxy Statement/Prospectus and any amendments thereto to 
which this consent has been filed as an exhibit.

Date: May 13, 1997                     /s/ Lois E. Silverman
                                       -------------------------------
                                       Lois E. Silverman




<PAGE>


                                  DIRECTOR'S CONSENT


     I hereby consent to being named as a Director of Concentra Managed Care, 
Inc. in the Joint Proxy Statement/Prospectus and any amendments thereto to 
which this consent has been filed as an exhibit.

Date: May 13, 1997                     /s/ George H. Conrades
                                       ---------------------------
                                       George H. Conrades




<PAGE>


                                  DIRECTOR'S CONSENT


     I hereby consent to being named as a Director of Concentra Managed Care, 
Inc. in the Joint Proxy Statement/Prospectus and any amendments thereto to 
which this consent has been filed as an exhibit.

Date: May 13, 1997                     /s/ Mitchell T. Rabkin, M.D.
                                       -------------------------------
                                       Mitchell T. Rabkin, M.D.




<PAGE>
                                                            EXHIBIT 99.7


        



       CONSENT OF DONALDSON, LUFKIN & JENRETTE SECURITIES CORPORATION


    We hereby consent to (i) the inclusion of our opinion letter, dated
April 21, 1997, to the Board of Directors of OccuSystems, Inc. (the 
"Company") as Appendix D to the Joint Proxy Statement/Prospectus of the 
Company, CRA Managed Care, Inc. ("CRA") and Concentra Managed Care, Inc. 
("Concentra") relating to the merger of the Company with and into Concentra 
and the merger of a wholly owned subsidiary of Concentra with and into CRA, 
and (ii) all references to DLJ in the sections captioned "SUMMARY -- the 
Mergers"; "THE MERGERS -- Background of the Mergers"; "-- Recommendation of 
OccuSystems Board; OccuSystems' Reasons for the Mergers"; and "-- Opinions of 
Financial Advisors" of the Joint Proxy Statement/Prospectus of the Company, 
CRA and Concentra which forms a part of this Registration Statement on 
Form S-4. In giving such consent, we do not admit that we come within the 
category of persons whose consent is required under, and we do not admit that 
we are "experts" for purposes of, the Securities Act of 1933, as amended, and 
the rules and regulations promulgated thereunder.


                                        DONALDSON, LUFKIN & JENRETTE
                                            SECURITIES CORPORATION



                                        By: /s/ William G. Payne
                                            ---------------------------
                                            William G. Payne
                                            Vice President


Dallas, Texas
May 14, 1997


<PAGE>



CRA Managed Care, Inc.
312 Union Wharf
Boston, Massachusetts 02109


Members of the Board:

     We hereby consent to the inclusion of our opinion letter to the Board of 
Directors of CRA Managed Care, Inc. ("CRA") as Appendix E to the Joint Proxy 
Statement/Prospectus of CRA and OccuSystems, Inc. ("OccuSystems") relating to 
the proposed merger transaction involving CRA and OccuSystems. In giving such 
consent, we do not admit that we come within the category of persons whose 
consent is required under, and we do not admit that we are "experts" for 
purposes of, the Securities Act of 1933, as amended, and the rules and 
regulations promulgated thereunder.





                                              ALEX. BROWN & SONS INCORPORATED



Baltimore, Maryland
May 14, 1997





<PAGE>
                                                      EXHIBIT 99.2



                              ARTHUR ANDERSEN LLP

                  CONSENT OF INDEPENDENT PUBLIC ACCOUNTANTS


As independent public accountants, we hereby consent to the incorporation by 
reference in this Form 8-K of our reports dated January 27, 1997 which are 
incorporated by reference and included in CRA Managed Care, Inc.'s Form 10-K 
for the year ended December 31, 1996. CRA Managed Care, Inc.'s Form 10-K is 
incorporated by reference in the Form S-4 of Concentra Managed Care, Inc. 
(Registration No. 333-27105) which is included as an exhibit to this Form 
8-K. We also consent to all references to our Firm included in the Form S-4.


                                                   /s/ Arthur Andersen LLP
                                                   ARTHUR ANDERSEN LLP

Boston, Massachusetts
May 15, 1997





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