VANGUARD ASSET ALLOCATION FUND INC
497, 2000-01-25
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<PAGE>
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                       SECURITIES AND EXCHANGE COMMISSION
                             WASHINGTON, D.C. 20549

                                   FORM N-1A

     REGISTRATION STATEMENT (NO. 33-23444) UNDER THE SECURITIES ACT OF 1933

                           PRE-EFFECTIVE AMENDMENT NO.
                        POST-EFFECTIVE AMENDMENT NO. 16

                                      AND

        REGISTRATION STATEMENT UNDER THE INVESTMENT COMPANY ACT OF 1940

                                AMENDMENT NO. 19

                         VANGUARD ASSET ALLOCATION FUND
        (EXACT NAME OF REGISTRANT AS SPECIFIED IN DECLARATION OF TRUST)

                     P.O. BOX 2600, VALLEY FORGE, PA 19482
                    (ADDRESS OF PRINCIPAL EXECUTIVE OFFICE)

                  REGISTRANT'S TELEPHONE NUMBER (610) 669-1000

                           R. GREGORY BARTON, ESQUIRE
                                  P.O. BOX 876
                             VALLEY FORGE, PA 19482


               IT IS PROPOSED THAT THIS FILING BECOME EFFECTIVE:
          ON JANUARY 25, 2000, PURSUANT TO PARAGRAPH (B) OF RULE 485.

                 APPROXIMATE DATE OF PROPOSED PUBLIC OFFERING:
  AS SOON AS PRACTICABLE AFTER THIS REGISTRATION STATEMENT BECOMES EFFECTIVE.


WE HAVE  ELECTED  TO  REGISTER  AN  INDEFINITE  NUMBER OF  SECURITIES  UNDER THE
SECURITIES ACT OF 1933 PURSUANT TO RULE 24F-2 OF THE  INVESTMENT  COMPANY ACT OF
1940. REGISTRANT FILED ITS RULE 24F-2 NOTICE FOR ITS FISCAL YEAR ENDED SEPTEMBER
30, 1999 WITH THE COMMISSION ON DECEMBER 29, 1999.
================================================================================
<PAGE>
                         VANGUARD ASSET ALLOCATION FUND
                             CROSS REFERENCE SHEET
<TABLE>
<CAPTION>
<S>                                                    <C>
FORM N-1A
ITEM NUMBER                                            LOCATION IN PROSPECTUS
- ----------------------------------------------------------------------------------------------------
Item 1. Front and Back Cover Pages ....................Front and Back Cover Pages

Item 2. Risk/Return Summary; Investments, Risk, and
        Performance ...................................Fund Profile

Item 3. Risk/Return Summary: Fee Table ................Fee Table


Item 4. Investment Objectives, Princial Investment
        Strategies, and Related Risks .................A Word About Risk; Who Should Invest;
                                                       Primary Investment Strategies
Item 5. Management's Discussion of Fund
        Performance ...................................Herein incorporated by reference to
                                                       Registrant's Annual Report to Shareholders
                                                       dated September 30, 1999 filed with the
                                                       Securities & Exchange Commission's EDGAR
                                                       system November 17, 1999.

Item 6. Management, Organization, and Capital
        Structure .....................................The Fund and Vanguard; Investment Adviser

Item 7. Shareholder Information .......................Share Price; Dividends, Capital Gains, and
                                                       Taxes; Investing with Vanguard

Item 8. Distribution Arrangements .....................Not Applicable

Item 9. Financial Highlights Information ..............Financial Highlights

FORM N-1A                                              LOCATION IN STATEMENT OF ADDITIONAL
ITEM NUMBER                                            INFORMATION
- ----------------------------------------------------------------------------------------------------
Item 10.Cover Page and Table of Contents ..............Cover Page; Table of Contents

Item 11.Fund History ..................................Description of the Fund

Item 12.Description of the Fund and its Investments
        and Risks .....................................Investment Policies; Description of the Fund;
                                                       Fundamental Investment Limitations

Item 13.Management of the Fund ........................Management of the Fund

Item 14.Control Persons and Principal Holders of
        Securities ....................................Management of the Fund

Item 15.Investment Advisory and Other Services ........Investment Advisory Services

Item 16.Brokerage Allocation and Other Practices ......Portfolio Transactions

Item 17.Capital Stock and Other Securities ............Description of the Fund

Item 18.Purchase, Redemption, and Pricing of Shares ...Purchase of Shares; Redemption of Shares;
                                                       Share Price

Item 19.Taxation of the Fund ..........................Description of the Fund

Item 20.Underwriters ..................................Not Applicable

Item 21.Calculation of Performance Data ...............Yield and Total Return

Item 22.Financial Statements ..........................Financial Statements
</TABLE>

<PAGE>
VANGUARD(R)
ASSET ALLOCATION
FUND

Prospectus
January 21, 2000

This  prospectus  contains  financial  data for the Fund through the fiscal year
ended September 30, 1999.

[SHIP GRAPHIC]
[A MEMBER OF THE VANGUARD GROUP(R) LOGO]
<PAGE>

VANGUARD ASSET ALLOCATION FUND
Prospectus
January 21, 2000

An Asset Allocation Mutual Fund

- --------------------------------------------------------------------------------
   CONTENTS
- --------------------------------------------------------------------------------
 1 FUND PROFILE                           12 FINANCIAL HIGHLIGHTS

 3 ADDITIONAL INFORMATION                 14 INVESTING WITH VANGUARD

 3 A WORD ABOUT RISK                      14 SERVICES AND ACCOUNT FEATURES

 3 WHO SHOULD INVEST                      15 TYPES OF ACCOUNTS

 4 PRIMARY INVESTMENT STRATEGIES          16 BUYING SHARES

 9 THE FUND AND VANGUARD                  18 REDEEMING SHARES

 9 INVESTMENT ADVISER                     21 TRANSFERRING REGISTRATION

 10 DIVIDENDS, CAPITAL GAINS, AND TAXES   22 FUND AND ACCOUNT UPDATES

 12 SHARE PRICE                           GLOSSARY (inside back cover)
- --------------------------------------------------------------------------------

- --------------------------------------------------------------------------------
 WHY READING THIS PROSPECTUS IS IMPORTANT
 This prospectus explains the objective, risks, and strategies of Vanguard Asset
 Allocation  Fund.  To  highlight  terms and  concepts  important to mutual fund
 investors,  we have  provided  "Plain  Talk(R)"  explanations  along the way.
 Reading the  prospectus  will help you to decide  whether the Fund is the right
 investment for you. We suggest that you keep it for future reference.
- --------------------------------------------------------------------------------
NEITHER  THE  SECURITIES  AND  EXCHANGE  COMMISSION  NOR  ANY  STATE  SECURITIES
COMMISSION HAS APPROVED OR  DISAPPROVED  OF THESE  SECURITIES OR PASSED UPON THE
ACCURACY OR ADEQUACY OF THIS PROSPECTUS. ANY REPRESENTATION TO THE CONTRARY IS A
CRIMINAL OFFENSE.

<PAGE>
                                                                               1

FUND PROFILE

The following profile summarizes key features of Vanguard Asset Allocation Fund.

INVESTMENT OBJECTIVE
The Fund seeks to provide  maximum  long-term  total return (capital change plus
income) while  incurring  less stock market risk than a fund made up entirely of
stocks.

INVESTMENT STRATEGIES
The Fund  invests in common  stocks,  bonds,  and money  market  instruments  in
proportions  consistent  with their expected  returns and risks, as evaluated by
the Fund's  adviser.  These  proportions are changed from time to time as market
expectations  shift. The Fund is permitted to be 100% invested in any one of the
three asset classes.

PRIMARY RISKS

THE FUND'S TOTAL RETURN,  LIKE STOCK AND BOND PRICES  GENERALLY,  WILL FLUCTUATE
WITHIN A WIDE  RANGE,  SO AN  INVESTOR  COULD LOSE MONEY OVER SHORT OR EVEN LONG
PERIODS.  The Fund is also subject to:
o    Interest  rate risk,  which is the chance  that bond  prices  overall  will
     decline over short or even long periods due to rising interest rates.
o    Manager risk,  which is the chance that poor security  selection will cause
     the Fund to underperform other funds with similar investment objectives.

PERFORMANCE/RISK INFORMATION

The bar chart and table below  provide an indication of the risk of investing in
the Fund. The bar chart shows the Fund's  performance in each calendar year over
a ten-year  period.  The table shows how the Fund's average annual total returns
for one, five, and ten calendar years compare with those of a broad-based market
index and a composite index.  Keep in mind that the Fund's past performance does
not indicate how it will perform in the future.


              ----------------------------------------------------
                              ANNUAL TOTAL RETURNS
              ----------------------------------------------------
                                 [BAR CHART]
                    1990  0.89%         1995 35.46%
                    1991 25.59%         1996 15.73%
                    1992  7.51%         1997 27.32%
                    1993 13.49%         1998 25.40%
                    1994 -2.32%         1999  5.21%
              ----------------------------------------------------
     During the period shown in the bar chart, the highest return for a calendar
quarter was 14.31% (quarter ended December 31, 1998) and the lowest return for a
quarter was -8.31% (quarter ended March 31, 1990).

- --------------------------------------------------------------------------------
          AVERAGE ANNUAL TOTAL RETURNS FOR YEARS ENDED DECEMBER 31, 1999
- --------------------------------------------------------------------------------
                                      1 YEAR          5 YEARS        10 YEARS
- --------------------------------------------------------------------------------
Vanguard Asset Allocation Fund          5.21%         21.37%            14.80%
S&P 500 Index                          21.04          28.56             18.21
Composite Index*                        9.90          21.70             14.95
- --------------------------------------------------------------------------------
*Weighted 65% in the S&P 500 Index, 35% in the Lehman Brothers Long U.S.Treasury
 Bond Index.
- --------------------------------------------------------------------------------
<PAGE>


2
FEES AND EXPENSES

The following table describes the fees and expenses you would pay if you buy and
hold shares of the Fund. The expenses shown under Annual Fund Operating Expenses
are based upon those incurred in the fiscal year ended September 30, 1999.



      SHAREHOLDER FEES (fees paid directly from your investment)
      Sales Charge (Load) Imposed on Purchases:                          None
      Sales Charge (Load) Imposed on Reinvested Dividends:               None
      Redemption Fee:                                                    None
      Exchange Fee:                                                      None

      ANNUAL FUND OPERATING EXPENSES (expenses deducted from the Fund's assets)
      Management Expenses:                                               0.47%
      12b-1 Distribution Fee:                                            None
      Other Expenses:                                                    0.02%
       TOTAL ANNUAL FUND OPERATING EXPENSE S:                            0.49%

 The following  example is intended to help you compare the cost of investing in
the Fund with the cost of investing in other mutual funds.  It  illustrates  the
hypothetical  expenses  that you would incur over various  periods if you invest
$10,000 in the Fund.  This example assumes that the Fund provides a return of 5%
a year, and that operating  expenses  remain the same. The results apply whether
or not you redeem your investment at the end of each period.

               -------------------------------------------------
                 1 YEAR      3 YEARS      5 YEARS      10 YEARS
               -------------------------------------------------
                   $50         $157         $274          $616
               -------------------------------------------------

  THIS EXAMPLE SHOULD NOT BE CONSIDERED TO REPRESENT ACTUAL PERFORMANCE FROM THE
PAST OR FOR THE FUTURE. ACTUAL FUTURE EXPENSES MAY BE HIGHER OR LOWER THAN THOSE
SHOWN.

- --------------------------------------------------------------------------------
                               PLAIN TALK ABOUT
                                 FUND EXPENSES
All mutual funds have operating  expenses.  These  expenses,  which are deducted
from a fund's gross  income,  are expressed as a percentage of the net assets of
the fund. Vanguard Asset Allocation Fund's expense ratio in fiscal year 1999 was
0.49%,  or $4.90 per $1,000 of average net assets.  The average  flexible mutual
fund had  expenses in 1998 of 1.41%,  or $14.10 per $1,000 of average net assets
(derived  from data  provided by Lipper Inc.,  which  reports on the mutual fund
industry).
- --------------------------------------------------------------------------------
<PAGE>
                                                                               3

- --------------------------------------------------------------------------------
                               PLAIN TALK ABOUT
                            THE COSTS OF INVESTING

 Costs are an important  consideration in choosing a mutual fund. That's because
 you, as a shareholder,  pay the costs of operating a fund, plus any transaction
 costs associated with the fund's buying and selling of securities.  These costs
 can erode a substantial  portion of the gross income or capital  appreciation a
 fund  achieves.  Even seemingly  small  differences in expenses can, over time,
 have a dramatic effect on a fund's performance.
- --------------------------------------------------------------------------------

- --------------------------------------------------------------------------------
ADDITIONAL INFORMATION

DIVIDENDS AND CAPITAL GAINS                         MINIMUM INITIAL INVESTMENT
Dividends are distributed in June and December;     $3,000; $1,000 for IRAs and
capital gains, if any, are distributed in December  custodial accountsfor minors

INVESTMENT ADVISER                                  NEWSPAPER ABBREVIATION
Mellon Capital Management Corporation, San          AssetA
Francisco, Calif., since inception

INCEPTION DATE                                      VANGUARD FUND NUMBER
November 3, 1988                                    078

NET ASSETS AS OF SEPTEMBER 30, 1999                 CUSIP NUMBER
$8.18 billion                                       922020102

SUITABLE FOR IRAs                                   TICKER SYMBOL
Yes                                                 VAAPX
- --------------------------------------------------------------------------------

================================================================================
A WORD ABOUT RISK

This prospectus  describes risks you would face as an investor in Vanguard Asset
Allocation  Fund.  It is  important  to keep in mind one of the main  axioms  of
investing: The higher the risk of losing money, the higher the potential reward.
The  reverse,  also,  is  generally  true:  The lower  the  risk,  the lower the
potential  reward.  As you consider an investment in Vanguard  Asset  Allocation
Fund,  you should also take into account your  personal  tolerance for the daily
fluctuations of the stock market.
     Look for this [FLAG ICON] symbol  throughout the prospectus.  It is used to
mark detailed  information  about each type of risk that you would confront as a
shareholder of the Fund.
================================================================================

WHO SHOULD INVEST

The Fund may be a suitable investment for you if:
o    You wish to  invest in a fund that  actively  manages a mix of U.S.  common
     stocks, bonds, and money market instruments.
o    You are seeking growth of capital over the long term--at least five years.
o    You are not looking for current income.

 THE VANGUARD FUNDS DO NOT PERMIT MARKET-TIMING. DO NOT INVEST IN THIS FUND IF
YOU ARE A MARKET-TIMER.
<PAGE>

4
- --------------------------------------------------------------------------------
                               PLAIN TALK ABOUT
                            COSTS AND MARKET-TIMING
 Some  investors  try  to  profit  from   market-timing--switching   money  into
 investments  when they expect  prices to rise,  and taking  money out when they
 expect  the  market to fall.  As money is  shifted  in and out,  a fund  incurs
 expenses for buying and selling  securities.  These costs are borne by all fund
 shareholders,  including the long-term investors who do not generate the costs.
 Therefore,  the Fund  discourages  short-term  trading by, among other  things,
 limiting the number of exchanges it permits.
- --------------------------------------------------------------------------------

     The Fund has adopted the following  policies,  among others,  to discourage
short-term trading:

o    The Fund  reserves  the right to  reject  any  purchase  request--including
     exchanges from other  Vanguard  funds--that it regards as disruptive to the
     efficient  management  of the Fund.  A purchase  request  could be rejected
     because  of the  timing  of the  investment  or  because  of a  history  of
     excessive trading by the investor.
o    There is a limit on the  number of times you can  exchange  into and out of
     the Fund (see "Redeeming Shares" in the INVESTING WITH VANGUARD section).
o    The Fund reserves the right to stop offering shares at any time.

PRIMARY INVESTMENT STRATEGIES

This section explains the strategies that the investment adviser uses in pursuit
of the  Fund's  objective,  long-term  growth of  capital  and  income.  It also
explains how the adviser implements these strategies.  In addition, this section
discusses several important  risks--market risk, interest rate risk, and manager
risk--faced by investors in the Fund. The Fund's Board of Trustees  oversees the
management of the Fund, and may change the investment strategies in the interest
of  shareholders.  Note  that  the  investment  objective  of  the  Fund  is not
fundamental, and may be changed without a shareholder vote.


MARKET EXPOSURE
The adviser, Mellon Capital Management Corporation,  allocates the Fund's assets
among stocks,  bonds, and money market instruments in proportions that depend on
projected returns and risks for each asset class.

STOCKS
A portion of the Fund's assets is typically invested in common stocks.

[FLAG] THE FUND IS SUBJECT TO STOCK MARKET RISK,  WHICH IS THE POSSIBILITY  THAT
     STOCK PRICES  OVERALL WILL DECLINE OVER SHORT OR EVEN LONG  PERIODS.  STOCK
     MARKETS TEND TO MOVE IN CYCLES,  WITH PERIODS OF RISING  PRICES AND PERIODS
     OF FALLING PRICES.

 The Fund  will  typically  hold a  diversified  combination  of  common  stocks
intended to parallel the performance of the S&P 500 Index, which is dominated by
large-capitalization   stocks.  The  stocks  are  evaluated  using  a  "dividend
discount" model.  This model provides an estimate of the total return of the S&P
500 Index,  based upon the  expected  earnings of each of the  companies  in the
index.

<PAGE>

                                                                               5

     To illustrate the volatility of stock prices, the following table shows the
best,  worst,  and average total returns for the U.S.  stock market over various
periods as measured by the Standard & Poor's 500 Index,  a widely used barometer
of market  activity.  (Total returns  consist of dividend  income plus change in
market  price.)  Note that the returns  shown do not include the costs of buying
and selling  stocks or other  expenses  that a real-world  investment  portfolio
would  incur.  Note,  also,  that the gap between best and worst tends to narrow
over the long term.


- --------------------------------------------------------------------------------
                      U.S. STOCK MARKET RETURNS (1926-1999)
- --------------------------------------------------------------------------------
                         1 YEAR         5 YEARS        10 YEARS       20 YEARS
- --------------------------------------------------------------------------------
Best                      54.2%           24.1%          19.9%          17.7%
Worst                    -43.1           -12.4           -0.8            3.1
Average                   13.1            10.7           11.0           11.0
- --------------------------------------------------------------------------------
     The table  covers all of the 1-, 5-,  10-,  and 20-year  periods  from 1926
through 1998. You can see, for example,  that while the average return on stocks
for all of the 5-year periods was 10.7%,  returns for individual  5-year periods
ranged  from a -12.4%  average  (from  1928  through  1932) to 24.1%  (from 1994
through 1998).  These average returns reflect past performance on common stocks;
you should not regard them as an  indication  of future  returns from either the
stock market as a whole or this Fund in particular.


BONDS
A portion of the Fund's assets is typically invested in bonds.

[FLAG] THE FUND IS SUBJECT TO INTEREST RATE RISK,  WHICH IS THE POSSIBILITY THAT
     BOND PRICES  OVERALL  WILL  DECLINE  OVER SHORT OR EVEN LONG PERIODS DUE TO
     RISING INTEREST RATES.

 Although bonds are often thought to be less risky than stocks,  there have been
periods when bond prices have fallen significantly due to rising interest rates.
For instance, prices of long-term bonds fell by almost 48% between December 1976
and September 1981.

- --------------------------------------------------------------------------------
                               PLAIN TALK ABOUT
                           BONDS AND INTEREST RATES

As a rule,  when  interest  rates rise,  bond prices fall.  The opposite is also
true:  Bond  prices go up when  interest  rates  fall.  Why do bond  prices  and
interest  rates move in opposite  directions?  Let's assume that you hold a bond
offering a 5% yield. A year later,  interest rates are on the rise and bonds are
offered with a 6% yield. With  higher-yielding  bonds available,  you would have
trouble selling your 5% bond for the price you  paid--causing  you to lower your
asking  price.  On the other hand,  if interest  rates were falling and 4% bonds
were  being  offered,  you should be able to sell your 5% bond for more than you
paid.
- --------------------------------------------------------------------------------
     To illustrate the relationship  between bond prices and interest rates, the
following  table shows the effect of a 1% and a 2% change  (both up and down) in
interest rates on three bonds of different maturities, each with a face value of
$1,000.

<PAGE>
6
<TABLE>
<CAPTION>
- ------------------------------------------------------------------------------------------------------------
                                         HOW INTEREST RATE CHANGES AFFECT BONDS*
- ------------------------------------------------------------------------------------------------------------
                              VALUE OF A $1,000   VALUE OF A $1,000   VALUE OF A $1,000    VALUE OF A $1,000
                              BOND AFTER A 2%     BOND AFTER A 2%     BOND AFTER A 1%      BOND AFTER A 1%
                                 INCREASE            DECREASE            INCREASE             DECREASE
TYPE OF BOND (MATURITY)       IN INTEREST RATES   IN INTEREST RATES   IN INTEREST RATES    IN INTEREST RATES
- ------------------------------------------------------------------------------------------------------------
<S>                                 <C>               <C>                 <C>                  <C>

Short-Term (2.5 years)              $978              $1,023               $956                $1,046
Intermediate-Term (10 years)         932               1,074                870                 1,156
Long-Term (20 years)                 901               1,116                816                 1,251
- ------------------------------------------------------------------------------------------------------------
*Assuming a 7% yield.
- ------------------------------------------------------------------------------------------------------------
</TABLE>

     The  Fund  will  typically  invest  its  allocation  to  bonds in a pool of
long-term U.S. Treasury bonds,  which mature in 10 to 30 years. It may also hold
other "full faith and credit" obligations of the U.S. government.

     The U.S. government guarantees the timely payment of interest and principal
for its Treasury  bonds,  but does not  guarantee  its bonds'  prices.  In other
words, while Treasury bonds enjoy the highest credit ratings, their prices--like
the prices of other bonds in the  Fund--will  fluctuate with changes in interest
rates.
     The  adviser  evaluates  bonds'  attractiveness  based upon  their  current
yield-to-maturity,  which is an estimate of total return that considers a bond's
purchase price,  redemption  value,  time to maturity,  yield,  and time between
interest payments.

- --------------------------------------------------------------------------------
                               PLAIN TALK ABOUT
                                TYPES OF BONDS

Bonds are issued (sold) by many sources: Corporations issue corporate bonds; the
federal  government  issues  U.S.  Treasury  bonds;   agencies  of  the  federal
government  issue agency bonds;  and mortgage  holders  issue  "mortgage-backed"
bonds,  such as those of the Government  National Mortgage  Association  (GNMA).
Each issuer is  responsible  for paying back the bond's initial value as well as
making periodic interest payments.
- --------------------------------------------------------------------------------
- --------------------------------------------------------------------------------
                                PLAIN TALK ABOUT
                                BOND MATURITIES

 A bond is issued with a specific maturity  date--the date when the bond issuer,
 or seller,  must pay back the bond's initial value (known as its "face value").
 Bond  maturities  generally  range from less than one year  (short-term)  to 30
 years (long-term).  The longer a bond's maturity,  the more risk you, as a bond
 investor,  face as interest  rates  rise--but  also the more interest you could
 receive.  Long-term  bonds are more  suitable  for  investors  willing  to take
 greater risks in hope of higher yields;  short-term  bond  investors  should be
 willing to accept lower yields in return for less  fluctuation  in the value of
 their investment.
- --------------------------------------------------------------------------------

SECURITY SELECTION
Mellon Capital  Management  Corporation  (Mellon Capital),  adviser to the Fund,
makes no  effort  to  choose  among  individual  stocks  or  bonds  to  identify
attractive securities. Rather, the adviser tries to determine the mix of stocks,
bonds,  and  money  market  instruments  that  offers  the best  combination  of
potential  return and risk. The aim is to maximize the long-term total return of
the Fund  while  incurring  less  stock  market  risk than a  portfolio

<PAGE>

                                                                               7

made up entirely of stocks.  At any given time, Mellon Capital may allocate all,
a portion,or  none of the Fund's  assets to  large-capitalization  U.S.  stocks,
long-term U.S. Treasury bonds, or cash reserves.
     For the Fund's  common stock  allocation,  the adviser  uses a  diversified
portfolio of stocks selected to parallel the performance of the S&P 500 Index or
S&P 500 stock index futures.  For the Fund's bond  allocation,  the adviser uses
long-term (10- to 30-year  maturities) U.S.  Treasury bonds and/or U.S. Treasury
Bond futures  and/or U.S.  Treasury Note  futures.  For the Fund's cash reserves
allocation, the adviser can use a variety of money market instruments, including
U.S.  Treasury bills,  government  agency  securities,  high-quality  commercial
paper, and certificates of deposit.
     Mellon  Capital  uses a computer  model to estimate  return and risk and to
recommend  shifts in  allocations.  The  adviser  implements  these  shifts in a
disciplined  manner.  The adviser believes that,  within the fluctuations of the
financial markets, there are occasional brief periods in which the market values
of the asset  classes do not  reflect  their true  value.  The Fund  attempts to
capitalize  on these  perceived  imbalances  by  changing  the mix of the Fund's
holdings in the three asset  classes.  There are no limitations on the amount of
the Fund's  assets  that may be  allocated  to stocks,  bonds,  or money  market
instruments; it can be 100% invested in any of the three asset classes.
     The Fund is generally managed without regard to tax ramifications.

[FLAG] THE FUND IS SUBJECT TO MANAGER RISK,  WHICH IS THE  POSSIBILITY  THAT THE
     ADVISER MAY DO A POOR JOB  ALLOCATING  THE FUND'S NET ASSETS AMONG  STOCKS,
     BONDS, AND MONEY MARKET INSTRUMENTS.

     Since the Fund's asset allocation changes according to the adviser's timely
projection  of risk and return,  the Fund may  exhibit  higher  volatility  than
balanced funds with static allocations.
     Historical  evidence indicates that correctly timing portfolio  allocations
among asset classes has been a difficult strategy to implement successfully on a
consistent  basis.  Although Mellon Capital has substantial  experience in asset
allocation,  there  can be no  assurance  that  the  adviser  will  consistently
anticipate which asset class will perform best in the future.
     The Fund's investment  results could suffer,  for example,  if only a small
portion of the Fund's assets were allocated to stocks during a significant stock
market  advance,  or if a major  portion of its assets were  allocated to stocks
during a market decline.  Similarly,  the Fund's short-term  investment  results
could also  suffer if the Fund were  substantially  invested  in bonds at a time
when interest rates increased.

TURNOVER RATE
Although the Fund  generally  seeks to invest for the long term,  it retains the
right to sell  securities  regardless of how long the securities have been held.
The Fund's average  turnover rate for the past five years has been about 32%. (A
turnover  rate of 100% would occur,  for example,  if the Fund sold and replaced
securities valued at 100% of its net assets within a one-year period.)


<PAGE>


8
- --------------------------------------------------------------------------------
                               PLAIN TALK ABOUT
                                 TURNOVER RATE
Before  investing in a mutual fund,  you should review its turnover  rate.  This
gives an  indication  of how  transaction  costs could affect the fund's  future
returns.  In general,  the greater the volume of buying and selling by the fund,
the greater the impact that brokerage  commissions and other  transaction  costs
will have on its return. Also, funds with high turnover rates may be more likely
to generate  capital gains that must be  distributed to  shareholders  as income
subject to taxes.  As of September 30, 1999,  the average  turnover rate for all
asset allocation funds was approximately 95%, according to Morningstar, Inc.
- --------------------------------------------------------------------------------



- --------------------------------------------------------------------------------
                                PLAIN TALK ABOUT
                                  DERIVATIVES

 A  derivative  is a financial  contract  whose value is based on (or  "derived"
 from) a traditional  security (such as a stock or a bond),  an asset (such as a
 commodity  like gold),  or a market index (such as the S&P 500 Index).  Futures
 and options are derivatives  that have been trading on regulated  exchanges for
 more  than  two  decades.  These  "traditional"  derivatives  are  standardized
 contracts  that can  easily be bought  and sold,  and whose  market  values are
 determined and published daily. It is these  characteristics that differentiate
 futures and options from the relatively new types of  derivatives.  If used for
 speculation or as leveraged  investments,  derivatives  can carry  considerable
 risks.
- --------------------------------------------------------------------------------

OTHER INVESTMENT POLICIES AND RISKS
Besides  investing in common stocks,  bonds, and money market  instruments,  the
Fund may make certain other kinds of investments to achieve its objective.
     The Fund may invest, to a limited extent, in foreign securities.
     The Fund may also invest in stock and bond  futures and options  contracts,
which are traditional  types of  derivatives.  Under normal  circumstances,  the
market  value of these  contracts  and  options may  represent  up to 50% of the
Fund's assets. (Under unusual circumstances,  the Fund may hold futures equal in
value to 100% of its net assets.)
     Losses (or gains) involving futures can sometimes be  substantial--in  part
because a relatively small price movement in a futures contract may result in an
immediate  and  substantial  loss (or gain)  for a fund.  This Fund will not use
futures for speculative  purposes.  The Fund will keep separate cash reserves or
short-term,   cash-equivalent   securities  in  the  amount  of  the  obligation
underlying the futures contract.
     The reasons for which the Fund will invest in futures and options are:
o    To hedge dividend accruals.
o    To keep cash on hand to meet  shareholder  redemptions or other needs while
     simulating full investment in stocks or bonds.
o    To reduce the Fund's  transaction costs or add value when these instruments
     are favorably priced.
o    To use as an investment tool when reallocating assets among stocks,  bonds,
     and  money  market  instruments.  For  example,  the  adviser  may  wish to
     reallocate 10% of the Fund's assets from stocks to bonds. To implement this
     change rapidly and with low transaction  costs,  the adviser may sell stock
     index futures and purchase bond index futures.
<PAGE>
                                                                               9

     The Fund may temporarily  depart from its normal  investment  policies--for
instance,   by  investing   substantially  in  cash  reserves--in   response  to
extraordinary market, economic, political, or other conditions. In doing so, the
Fund may succeed in avoiding losses but otherwise fail to achieve its investment
objective.

THE FUND AND VANGUARD

The Fund is a member of The Vanguard  Group, a family of more than 35 investment
companies  with more than 100 funds holding assets worth more than $530 billion.
All of the  Vanguard  funds  share  in the  expenses  associated  with  business
operations, such as personnel, office space, equipment, and advertising.

     Vanguard  also  provides   marketing   services  to  the  funds.   Although
shareholders do not pay sales commissions or 12b-1  distribution fees, each fund
pays its allocated share of The Vanguard Group's marketing costs.

- --------------------------------------------------------------------------------
                               PLAIN TALK ABOUT
                     VANGUARD'S UNIQUE CORPORATE STRUCTURE

 The Vanguard  Group is truly a MUTUAL mutual fund company.  It is owned jointly
 by the funds it  oversees  and thus  indirectly  by the  shareholders  in those
 funds. Most other mutual funds are operated by for-profit  management companies
 that may be owned by one person, by a group of individuals, or by investors who
 own the management company's stock. By contrast, Vanguard provides its services
 on an "at-cost"  basis, and the funds' expense ratios reflect only these costs.
 No separate  management  company reaps profits or absorbs losses from operating
 the funds.
- --------------------------------------------------------------------------------

INVESTMENT ADVISER

The Fund employs Mellon Capital  Management  Corporation,  595 Market St., Suite
3000, San Francisco,  CA 94105, as its investment  adviser.  Mellon Capital is a
wholly owned subsidiary of MBC Investment Corporation,  which itself is a wholly
owned subsidiary of Mellon Financial Corporation. Mellon Capital manages the
Fund subject to the control of the Trustees and officers of the Fund.
     Mellon  Capital's  advisory fee is paid at the end of each fiscal  quarter.
This fee is based on  certain  annual  percentage  rates  applied  to the Fund's
average  month-end  assets  for each  quarter.  In  addition,  Mellon  Capital's
advisory fee is  increased  or  decreased,  based on the  cumulative  investment
performance  of the Fund over a trailing  36-month  period as compared  with the
cumulative  total return of the Asset  Allocation  Composite  Index (65% S&P 500
Index; 35% Lehman Brothers Long U.S. Treasury Bond Index) over the same period.
     For the year ended September 30, 1999, the investment  advisory fee paid to
Mellon  Capital  represented  an  effective  annual  rate of 0.11% of the Fund's
average net assets before a decrease of 0.02% based on performance.
     The Fund has  authorized  Mellon  Capital  to choose  brokers or dealers to
handle the purchase and sale of securities  for the Fund,  and to seek to obtain
the best available  price and most  favorable  execution from these brokers with
respect to all transactions.
     In the interest of obtaining  better  execution  of a  transaction,  Mellon
Capital  may choose  brokers  who charge  higher  commissions.  If more than one
broker can obtain the best

<PAGE>
10

available  price and most  favorable  execution  of a  transaction,  then Mellon
Capital is  authorizedto  choose a broker  who, in  addition  to  executing  the
transaction, will provide research services to Mellon Capital or the Fund. Also,
the Fund may direct  Mellon  Capital  to use a  particular  broker  for  certain
transactions in exchange for commission rebates or research services provided to
the Fund.
     The Board of Trustees may, without prior approval from shareholders, change
the terms of an advisory agreement or hire a new investment adviser--either as a
replacement for an existing adviser or as an additional adviser. Any significant
change in the Fund's advisory  arrangements will be communicated to shareholders
in writing. In addition, as the Fund's sponsor and overall manager, The Vanguard
Group may provide investment advisory services to the Fund, on an at-cost basis,
at any time.

- --------------------------------------------------------------------------------
                               PLAIN TALK ABOUT
                              THE FUND'S ADVISER

Mellon Capital Management  Corporation is an investment advisory firm founded in
1983. As of September 30, 1999,  Mellon Capital managed more than $73 billion in
assets.  The managers  responsible for overseeing the  implementation  of Mellon
Capital's strategy for the Fund are:

WILLIAM L. FOUSE,  CFA,  Chairman  Emeritus of  Executive  Committee  for Mellon
Capital;  has worked in investment  management  since 1953;  with Mellon Capital
since its founding in 1983; B.A. and M.B.A.,  University of Kentucky.  Mr. Fouse
has managed the Fund since its inception in 1988.

THOMAS F. LOEB, Chairman,  Chief Executive Officer of Mellon Capital; has worked
in investment  management  since 1970; with Mellon Capital since its founding in
1983; B.A., Fairleigh Dickinson University;  M.B.A., University of Pennsylvania.
Mr. Loeb has managed the Fund since its inception in 1988.
- --------------------------------------------------------------------------------

DIVIDENDS, CAPITAL GAINS, AND TAXES


FUND DISTRIBUTIONS
The Fund distributes to shareholders virtually all of its net income (interest
and dividends, less expenses), as well as any capital gains realized from the
sale of its holdings. Income dividends generally are distributed in June and
December; capital gains distributions generally occur in December. You can
receive distributions of income dividends or capital gains in cash, or you can
have them automatically reinvested in more shares of the Fund.

BASIC TAX POINTS
Vanguard will send you a statement  each year showing the tax status of all your
distributions.  In addition,  taxable investors should be aware of the following
basic tax points:
o    Distributions  are taxable to you whether or not you reinvest these amounts
     in additional Fund shares.
o    Distributions   declared  in  December--if  paid  to  you  by  the  end  of
     January--are taxable as if received in December.
o    Any dividends and short-term  capital gains that you receive are taxable to
     you as ordinary income for federal income tax purposes.



<PAGE>
                                                                              11

o    Any  distributions  of net  long-term  capital  gains are taxable to you as
     long-term capital gains for federal income tax purposes, no matter how long
     you've owned shares in the Fund.
o    Capital gains  distributions  may vary  considerably from year to year as a
     result of the Fund's normal investment activities and cash flows.
o    A sale or exchange of Fund shares is a taxable  event.  This means that you
     may have a capital gain to report as income, or a capital loss to report as
     a deduction, when you complete your federal income tax return.
o    State and local  income  taxes may apply to any  dividend or capital  gains
     distributions  that you  receive,  as well as your gains or losses from any
     sale or exchange of Fund shares.

GENERAL INFORMATION
BACKUP  WITHHOLDING.   By  law,  Vanguard  must  withhold  31%  of  any  taxable
distributions  or  redemptions  from your  account if you do not provide us with
your   correct   taxpayer   identification   number  and  certify   that  it  is
correct.Similarly, Vanguard must withhold from your account if the IRS instructs
us to do so.
FOREIGN  INVESTORS.  The Vanguard funds  generally do not offer their shares for
sale outside of the United States.  Foreign  investors should be aware that U.S.
withholding and estate taxes may apply to any investments in Vanguard funds.
INVALID  ADDRESSES.  If a dividend or capital gains distribution check mailed to
your address of record is returned as undeliverable, Vanguard will automatically
reinvest  all future  distributions  until you  provide us with a valid  mailing
address.
TAX CONSEQUENCES.  This prospectus provides general tax information only. If you
are investing through a tax-deferred retirement account, such as an IRA, special
tax rules apply. Please consult your tax adviser for detailed  information about
a fund's tax consequences for you.

- --------------------------------------------------------------------------------
                               PLAIN TALK ABOUT
                                 DISTRIBUTIONS
As a  shareholder,  you are  entitled  to your share of the fund's  income  from
interest and dividends, and gains from the sale of investments. You receive such
earnings as either an income  dividend or a capital gains  distribution.  Income
dividends come from both the dividends that the fund earns from its holdings and
the  interest it receives  from its money market and bond  investments.  Capital
gains are realized  whenever the fund sells securities for higher prices than it
paid for them. These capital gains are either short-term or long-term  depending
on whether the fund held the  securities  for one year or less, or more than one
year.
- --------------------------------------------------------------------------------

- --------------------------------------------------------------------------------
                               PLAIN TALK ABOUT
                              "BUYING A DIVIDEND"
 Unless you are investing through a tax-deferred  retirement account (such as an
 IRA),  it is not to your  advantage to buy shares of a fund  shortly  before it
 makes a  distribution,  because  doing so can cost you money in taxes.  This is
 known as "buying a dividend."  For example:  On December 15, you invest $5,000,
 buying 250 shares for $20 each. If the fund pays a distribution of $1 per share
 on December 16, its share price would drop to $19 (not counting market change).
 You still have only $5,000 (250 shares x $19 = $4,750 in share value,  plus 250
 shares x $1 = $250 in distributions),  but you owe tax on the $250 distribution
 you  received--even  if you  reinvest  it in more  shares.  To avoid  "buying a
 dividend," check a fund's distribution schedule before you invest.
- --------------------------------------------------------------------------------
<PAGE>

12

SHARE PRICE

The Fund's share price,  called its net asset value,  or NAV, is calculated each
business day after the close of trading on the New York Stock  Exchange (the NAV
is not  calculated  on holidays or other days when the Exchange is closed).  Net
asset  value per share is  computed  by adding up the total  value of the Fund's
investments and other assets,  subtracting any of its liabilities  (debts),  and
then dividing by the number of Fund shares outstanding:

        NET ASSET VALUE =     TOTAL ASSETS - LIABILITIES
                           -------------------------------
                             NUMBER OF SHARES OUTSTANDING

 Knowing the daily net asset value is useful to you as a shareholder  because it
indicates the current value of your  investment.  The Fund's NAV,  multiplied by
the  number of  shares  you own,  gives you the  dollar  amount  you would  have
received had you sold all of your shares back to the Fund that day.
 A NOTE ON PRICING:  The Fund's investments will be priced at their market value
when market  quotations  are readily  available.  When these  quotations are not
readily  available,  investments will be priced at their fair value,  calculated
according to procedures adopted by the Fund's Board of Trustees.
 The Fund's  share price can be found daily in the mutual fund  listings of most
major newspapers under the heading "Vanguard  Funds."  Different  newspapers use
different abbreviations of the Fund's name, but the most common is ASSETA.

FINANCIAL HIGHLIGHTS

The following financial  highlights table is intended to help you understand the
Fund's financial  performance for the past five years,  and certain  information
reflects  financial  results for a single Fund share.  The total  returns in the
table represent the rate that an investor would have earned or lost each year on
an investment  in the Fund  (assuming  reinvestment  of all dividend and capital
gains  distributions).  This  information  has been derived  from the  financial
statements audited by PricewaterhouseCoopers LLP, independent accountants, whose
report--along  with the Fund's financial  statements--is  included in the Fund's
most recent annual report to  shareholders.  You may have the annual report sent
to you without charge by contacting Vanguard.

<PAGE>
                                                                              13
<TABLE>
<CAPTION>

- ------------------------------------------------------------------------------------------
                                                   VANGUARD ASSET ALLOCATION FUND
                                                       YEAR ENDED SEPTEMBER 30,
                                       ---------------------------------------------------
                                             1999       1998      1997      1996      1995
- ------------------------------------------------------------------------------------------
<S>                                          <C>      <C>       <C>       <C>       <C>
NET ASSET VALUE, BEGINNING OF YEAR           $22.90   $21.53    $18.27    $17.03    $13.78
- ------------------------------------------------------------------------------------------
INVESTMENT OPERATIONS
Net Investment Income                           .80      .79       .74       .69       .64
Net Realized and Unrealized Gain (Loss)on
 Investments                                   2.50     2.33      4.29      1.82      3.18
                                       ---------------------------------------------------
 Total from Investment Operations              3.30     3.12      5.03      2.51      3.82
                                       ---------------------------------------------------
DISTRIBUTIONS
Dividends from Net Investment Income          (.91)    (.74)     (.72)     (.66)     (.57)
Distributions from Realized Capital Gains    (1.18)   (1.01)    (1.05)     (.61)       --
                                       ---------------------------------------------------
 Total Distributions                         (2.09)   (1.75)    (1.77)    (1.27)     (.57)
- ------------------------------------------------------------------------------------------
NET ASSET VALUE, END OF YEAR                 $24.11   $22.90    $21.53    $18.27    $17.03
==========================================================================================

TOTAL RETURN                                 14.68%   15.24%    29.42%    15.27%    28.57%
==========================================================================================

RATIOS/SUPPLEMENTAL DATA
Net Assets, End of Year (Millions)           $8,182   $5,637    $3,738    $2,341    $1,593
Ratio of Total Expenses to Average Net Assets 0.49%    0.49%     0.49%     0.47%     0.49%
Ratio of Net Investment Income to
 Average Net Assets                           3.49%    3.80%     3.96%     4.17%     4.41%
Turnover Rate                                   11%      60%       10%       47%       34%
==========================================================================================
</TABLE>

- --------------------------------------------------------------------------------
                               PLAIN TALK ABOUT
                  HOW TO READ THE FINANCIAL HIGHLIGHTS TABLE

The Fund began  fiscal 1999 with a net asset value  (price) of $22.90 per share.
During  the  year,  the Fund  earned  $0.80  per share  from  investment  income
(interest  and  dividends)  and  $2.50  per  share  from  investments  that  had
appreciated  in value or that were sold for higher prices than the Fund paid for
them.

Shareholders  received $2.09 per share in the form of dividend and capital gains
distributions.  A portion of each year's  distributions  may come from the prior
year's income or capital gains.

The  earnings  ($3.30  per  share)  minus the  distributions  ($2.09  per share)
resulted in a share price of $24.11 at the end of the year. This was an increase
of $1.21 per share (from  $22.90 at the  beginning  of the year to $24.11 at the
end of the year).  For a shareholder  who  reinvested the  distributions  in the
purchase of more shares, the total return from the Fund was 14.68% for the year.

As of September  30,  1999,  the Fund had $8.18  billion in net assets.  For the
year, its expense ratio was 0.49% ($4.90 per $1,000 of net assets);  and its net
investment  income  amounted to 3.49% of its  average  net  assets.  It sold and
replaced securities valued at 11% of its net assets.
- --------------------------------------------------------------------------------
"Standard & Poor's(R),"  "S&P(R),"  "S&P  500(R),"  "Standard & Poor's 500," and
"500" are trademarks of The McGraw-Hill Companies, Inc.

<PAGE>
14
- --------------------------------------------------------------------------------
 INVESTING WITH VANGUARD
 Are you looking for the most  convenient way to open or add money to a Vanguard
 account? Obtain instant access to fund information?  Establish an account for a
 minor child or for your retirement savings?
  Vanguard  can  help.  Our goal is to make it easy and  pleasant  for you to do
 business with us.
  The following  sections of the prospectus briefly explain the many services we
 offer.  Booklets providing  detailed  information are available on the services
 marked with a [BOOK ICON]. Please call us to request copies.
- --------------------------------------------------------------------------------

SERVICES AND ACCOUNT FEATURES

Vanguard  offers many services that make it convenient to buy, sell, or exchange
shares, or to obtain fund or account information.
- --------------------------------------------------------------------------------
TELEPHONE REDEMPTIONS (SALES AND EXCHANGES)
Automatically set up for this Fund unless you notify us otherwise.
- --------------------------------------------------------------------------------
VANGUARD(R) DIRECT DEPOSIT SERVICE [BOOK]
Automatic  method  for  depositing  your  paycheck  or U.S.  government  payment
(including Social Security and government pension checks) into your account.
- --------------------------------------------------------------------------------
VANGUARD(R) AUTOMATIC EXCHANGE SERVICE [BOOK]
Automatic  method for  moving a fixed  amount of money  from one  Vanguard  fund
account to another.
- --------------------------------------------------------------------------------
VANGUARD FUND EXPRESS(R)[BOOK]
Electronic  method for buying or selling shares.  You can transfer money between
your  Vanguard  fund account and an account at your bank,  savings and loan,  or
credit union on a systematic schedule or whenever you wish.
- --------------------------------------------------------------------------------
VANGUARD DIVIDEND EXPRESS TM [BOOK]
Electronic method for transferring  dividend and/or capital gains  distributions
directly  from your  Vanguard  fund account to your bank,  savings and loan,  or
credit union account.
- --------------------------------------------------------------------------------
VANGUARD TELE-ACCOUNT(R) 1-800-662-6273 (ON-BOARD)[BOOK]
Toll-free  24-hour access to Vanguard fund and account  information--as  well as
some  transactions--by  using any touch-tone phone.  Tele-Account provides total
return,  share price, price change, and yield quotations for all Vanguard funds;
gives your account balances and history (e.g., last transaction, latest dividend
distribution);  and  allows  you to sell or  exchange  shares  to and from  most
Vanguard funds.
- --------------------------------------------------------------------------------
ACCESS VANGUARD TM www.vanguard.com [COMPUTER GRAPHIC]
You can use your  personal  computer to perform  certain  transactions  for most
Vanguard  funds by accessing our website.  To establish  this service,  you must
register  through our website.  We will then mail you an account access password
that  allows  you  to  process  the  following   financial  and   administrative
transactions online:

o Open a new account.*

o Buy, sell, or exchange shares of most funds.
o Change your name/address.
<PAGE>

                                                                              15
o Add / change fund options  (including dividend options, Vanguard Fund Express,
  bank instructions, checkwriting, and  Vanguard  Automatic  Exchange  Service).
  (Some restrictions may apply.) Please call our Client Services Department for
  assistance.

*Only current Vanguard shareholders can open a new account online, by exchanging
 shares from other existing Vanguard accounts.
- --------------------------------------------------------------------------------
INVESTOR INFORMATION DEPARTMENT: 1-800-662-7447(SHIP)
TEXT TELEPHONE: 1-800-952-3335
Call  Vanguard for  information  on our funds,  fund  services,  and  retirement
accounts, and to request literature.
- --------------------------------------------------------------------------------
CLIENT SERVICES DEPARTMENT: 1-800-662-2739 (CREW) TEXT TELEPHONE: 1-800-749-7273
Call Vanguard for information on your account, account transactions, and account
statements.
- --------------------------------------------------------------------------------
SERVICES  FOR  CLIENTS  OF  VANGUARD'S  INSTITUTIONAL  DIVISION:  1-888-809-8102
Vanguard's  Institutional  Division offers a variety of specialized services for
large  institutional   investors,   including  the  ability  to  effect  account
transactions through private electronic networks and third-party recordkeepers.
- --------------------------------------------------------------------------------

TYPES OF ACCOUNTS
Individuals and institutions can establish a variety of accounts with Vanguard.
- --------------------------------------------------------------------------------
FOR ONE OR MORE PEOPLE
Open an account in the name of one (individual) or more (joint tenants) people.
- --------------------------------------------------------------------------------
FOR HOLDING PERSONAL TRUST ASSETS [BOOK]
Invest assets held in an existing personal trust.
- --------------------------------------------------------------------------------
FOR INDIVIDUAL RETIREMENT ACCOUNTS [BOOK]
Open a  traditional  IRA account or a Roth IRA  account.  Eligibility  and other
requirements  are  established  by federal law and  Vanguard  custodial  account
agreements. For more information, please call 1-800-662-7447 (SHIP).
- --------------------------------------------------------------------------------
FOR AN ORGANIZATION [BOOK]
Open an account as a corporation,  partnership,  endowment, foundation, or other
entity.
- --------------------------------------------------------------------------------
FOR THIRD-PARTY TRUSTEE RETIREMENT INVESTMENTS
Open an account as a retirement trust or plan based on an existing  corporate or
institutional  plan.  These  accounts  are  established  by the  trustee  of the
existing plan.
- --------------------------------------------------------------------------------
VANGUARD PROTOTYPE PLANS
Open a  variety  of  retirement  accounts  using  Vanguard  prototype  plans for
individuals,  sole proprietorships,  and small businesses. For more information,
please call 1-800-662-2003.
- --------------------------------------------------------------------------------
A NOTE ON INVESTING WITH VANGUARD THROUGH OTHER FIRMS
You may purchase or sell Fund shares through a financial  intermediary such as a
bank,  broker,  or investment  adviser.  If you invest with Vanguard  through an
intermediary,  please read that firm's program  materials  carefully to learn of
any  special  rules  that may apply.  For  example,  special  terms may apply to
additional service features, fees, or other policies.  Consult your intermediary
to determine when your order will be priced.
- --------------------------------------------------------------------------------
<PAGE>

16

BUYING SHARES
You buy your shares at the Fund's next-determined net asset value after Vanguard
receives your request.  As long as your request is received  before the close of
trading on the New York Stock Exchange,  generally 4 p.m. Eastern time, you will
buy your shares at that day's net asset value.
- --------------------------------------------------------------------------------
MINIMUM INVESTMENT TO . . .
open a new account
$3,000 (regular account); $1,000 (traditional IRAs and Roth IRAs).

add to an existing account
$100 by mail or exchange; $1,000 by wire.
- --------------------------------------------------------------------------------
A NOTE ON LOW BALANCES
The Fund  reserves  the  right to close any  nonretirement  fund  account  whose
balance falls below the minimum initial  investment.  The Fund will deduct a $10
annual fee in June if your  nonretirement  account balance at that time is below
$2,500.  The low balance fee is waived for investors who have aggregate Vanguard
account assets of $50,000 or more.
- --------------------------------------------------------------------------------
BY MAIL TO . . .[ENVELOPE ICON]
open a new account
Complete and sign the account registration form and enclose your check.

add to an existing account
Mail your check with an  Invest-By-Mail  form  detached  from your  confirmation
statement to the address listed on the form. Please do not alter Invest-By-Mail
forms, since they are fund- and account-specific.

Make your check payable to: The Vanguard Group-78
All  purchases  must be made in U.S.  dollars,  and checks must be drawn on U.S.
banks.

First-class mail to:            Express or Registered mail to:
The Vanguard Group              The Vanguard Group
P.O. Box 1110                   455 Devon Park Drive
Valley Forge, PA 19482-2600     Wayne, PA 19087-1815

For clients of Vanguard's Institutional Division . . .

First-class mail to:            Express or Registered mail to:
The Vanguard Group              The Vanguard Group
P.O. Box 2900                   455 Devon Park Drive
Valley Forge, PA 19482-2900     Wayne, PA 19087-1815
- --------------------------------------------------------------------------------
IMPORTANT NOTE:  To prevent check fraud,  Vanguard will  not  accept checks made
payable to third parties.
- --------------------------------------------------------------------------------
BY TELEPHONE TO . . .[TELEPHONE ICON]
open a new account
Call Vanguard  Tele-Account*  24 hours a day--or Client Services during business
hours--to exchange from another Vanguard fund account with the same registration
(name, address, taxpayer identification number, and account type).
<PAGE>
                                                                              17
add to an existing account
Call Vanguard  Tele-Account*  24 hours a day--or Client Services during business
hours--to exchange from another Vanguard fund account with the same registration
(name, address,  taxpayer  identification  number, and account type). (Note that
some restrictions  apply to index fund accounts.) Use Vanguard Fund Express (see
Services and Account  Features) to transfer assets from your bank account.  Call
Client Services before your first use to verify that this option is available.

Vanguard Tele-Account           Client Services
1-800-662-6273                  1-800-662-2739

*You must obtain a Personal  Identification Number through Tele-Account at least
 seven days before you request your first exchange.
- --------------------------------------------------------------------------------
IMPORTANT  NOTE:  Once  you  have  initiated  a  telephone   transaction  and  a
confirmation  number has been assigned,  the transaction  cannot be revoked.  We
reserve the right to refuse any purchase request.
- --------------------------------------------------------------------------------
BY WIRE TO OPEN A NEW ACCOUNT OR ADD TO AN EXISTING ACCOUNT [WIRE ICON]
Call Client  Services to arrange your wire  transaction.  Wire  transactions  to
retirement  accounts are only  available for asset  transfers and rollovers from
other financial institutions.  Individual IRA contributions will not be accepted
by wire.

Wire to:
FRB ABA 021001088
HSBC Bank USA

For credit to:
Account: 000112046
Vanguard Incoming Wire Account

In favor of:
Vanguard Asset Allocation Fund-78
[Account number, or temporary number for a new account]
[Registered account owner(s)]
[Registered address]
- --------------------------------------------------------------------------------
You can redeem (that is, sell or exchange) shares purchased by check or Vanguard
Fund  Express  at any time.  However,  while  your  redemption  request  will be
processed  at the  next-determined  net asset value after it is  received,  your
redemption  proceeds  will not be available  until  payment for your purchase is
collected, which may take up to ten calendar days.
- --------------------------------------------------------------------------------
A NOTE ON LARGE PURCHASES

It is important that you call Vanguard  before you invest a large dollar amount.
It is our  responsibility to consider the interests of all Fund shareholders and
so we  reserve  the right to refuse any  purchase  that may  disrupt  the Fund's
operation or performance.
- --------------------------------------------------------------------------------
<PAGE>
18

REDEEMING SHARES
This section describes how you can redeem--that is, sell or exchange--the Fund's
shares.

When Selling Shares:
o    Vanguard sends the redemption proceeds to you or a designated third party.*
o    You can sell all or part of your Fund shares at any time.

*    May require a  signature  guarantee;  see  footnote on page 20.


When Exchanging Shares:
o    The redemption proceeds are used to purchase shares of a different Vanguard
     fund.
o    You must meet the receiving fund's minimum investment requirements.
o    Vanguard reserves the right to revise or terminate the exchange  privilege,
     limit the amount of an exchange, or reject an exchange at any time, without
     notice.
o    In  order  to  exchange  into  an  account  with a  different  registration
     (including a different name, address, or taxpayer  identification  number),
     you must include the guaranteed signatures of all current account owners on
     your written instructions.

In both  cases,  your  transaction  will be based on the Fund's  next-determined
share price,  subject to any special  rules  discussed in this  prospectus.

- --------------------------------------------------------------------------------
NOTE:  Once a redemption  is initiated  and a  confirmation  number  given,  the
transaction CANNOT be canceled.
- --------------------------------------------------------------------------------
HOW TO REQUEST A REDEMPTION
You can  request a  redemption from  your Fund  account  in any one of three
ways: online, by telephone, or by mail.
     The Vanguard funds whose shares you cannot  exchange online or by telephone
are VANGUARD U.S.  STOCK INDEX FUNDS,  VANGUARD  BALANCED  INDEX FUND,  VANGUARD
INTERNATIONAL  STOCK INDEX FUNDS,  VANGUARD REIT INDEX FUND, and VANGUARD GROWTH
AND INCOME FUND. These funds do, however,  permit online and telephone exchanges
within  IRAs and other  retirement  accounts.  If you sell shares of these funds
online, you will receive a redemption check at your address of record.
- --------------------------------------------------------------------------------
ONLINE REQUESTS [COMPUTER ICON]
ACCESS VANGUARD at www.vanguard.com
You can use your personal  computer to sell or exchange  shares of most Vanguard
funds by accessing our website.  To establish  this  service,  you must register
through our website.  We will then mail you an account access password that will
enable  you to sell  or  exchange  shares  online  (as  well  as  perform  other
transactions).
- --------------------------------------------------------------------------------
TELEPHONE REQUESTS [TELEPHONE ICON]
All Account Types Except Retirement:
Call Vanguard  Tele-Account  24 hours a day--or Client  Services during business
hours--to  sell or exchange  shares.  You can exchange  shares from this Fund to
open an account in another Vanguard fund or to add to an existing  Vanguard fund
account with an identical registration.

Retirement Accounts:
You can  exchange--but  not  sell--shares  by  calling  Tele-Account  or  Client
Services.
<PAGE>
                                                                              19

Vanguard Tele-Account           Client Services
1-800-662-6273                  1-800-662-2739
- --------------------------------------------------------------------------------
SPECIAL  INFORMATION:  We will automatically  establish the telephone redemption
option for your  account,  unless you instruct us  otherwise  in writing.  While
telephone  redemption is easy and convenient,  this account  feature  involves a
risk of loss from  unauthorized or fraudulent  transactions.  Vanguard will take
reasonable  precautions  to protect your  account from fraud.  You should do the
same by keeping your account information  private and immediately  reviewing any
account  statements  that  we  send  to  you.  Make  sure  to  contact  Vanguard
immediately about any transaction you believe to be unauthorized.
- --------------------------------------------------------------------------------
We reserve the right to refuse a telephone redemption if the caller is unable to
provide:
o    The ten-digit account number.
o    The name and address EXACTLY as registered on the account.
o    The primary Social Security or employer identification number as registered
     on the account.
o    The  Personal   Identification   Number,   if  applicable   (for  instance,
     Tele-Account).
     Please note that Vanguard will not be  responsible  for any account  losses
due to telephone  fraud, so long as we have taken reasonable steps to verify the
caller's identity.  If you wish to remove the telephone  redemption feature from
your account, please notify us in writing.
- --------------------------------------------------------------------------------
A NOTE ON UNUSUAL CIRCUMSTANCES
Vanguard  reserves the right to revise or  terminate  the  telephone  redemption
privilege at any time,  without notice.  In addition,  Vanguard can stop selling
shares or postpone  payment at times when the New York Stock  Exchange is closed
or under any emergency  circumstances  as determined by the U.S.  Securities and
Exchange Commission.  If you experience difficulty making a telephone redemption
during  periods  of  drastic  economic  or market  change,  you can send us your
request  by  regular or express  mail.  Follow  the  instructions  on selling or
exchanging shares by mail in this section.
- --------------------------------------------------------------------------------
MAIL REQUESTS [ENVELOPE ICON]
All Account Types Except Retirement:
Send a letter of instruction signed by all registered  account holders.  Include
the fund name and  account  number and (if you are  selling) a dollar  amount or
number  of shares  OR (if you are  exchanging)  the name of the fund you want to
exchange  into and a dollar  amount or number of  shares.  To  exchange  into an
account  with a different  registration  (including a different  name,  address,
taxpayer identification number, or account type), you must provide Vanguard with
written  instructions  that  include the  guaranteed  signatures  of all current
owners of the fund from which you wish to redeem.

Vanguard Retirement Accounts:
For information on how to request distributions from:
o    Traditional IRAs and Roth IRAs--call Client Services.
o    SEP-IRAs, SIMPLE IRAs, 403(b)(7) custodial accounts, and Profit-Sharing and
     Money Purchase Pension (Keogh) Plans--call  Individual  Retirement Plans at
     1-800-662-2003.

Depending on your account  registration  type,  additional  documentation may be
required.

First-class mail to:            Express or Registered mail to:
The Vanguard Group              The Vanguard Group
P.O. Box 1110                   455 Devon Park Drive
Valley Forge, PA 19482-1110     Wayne, PA 19087-1815
<PAGE>
20
For clients of Vanguard's Institutional Division . . .

First-class mail to:            Express or Registered mail to:
The Vanguard Group              The Vanguard Group
P.O. Box 2900                   455 Devon Park Drive
Valley Forge, PA 19482-2900     Wayne, PA 19087-1815
- --------------------------------------------------------------------------------
A NOTE ON LARGE REDEMPTIONS
It is important that you call Vanguard  before you redeem a large dollar amount.
It is our responsibility to consider the interests of all fund shareholders, and
so we reserve the right to delay  delivery of your  redemption  proceeds--up  to
seven days--if the amount may disrupt the Fund's operation or performance.
     If you redeem more than  $250,000  worth of Fund  shares  within any 90-day
period,  the  Fund  reserves  the  right  to pay  part or all of the  redemption
proceeds above $250,000  in-kind,  i.e., in securities,  rather than in cash. If
payment is made in-kind,  you may incur  brokerage  commissions  if you elect to
sell the securities for cash.
- --------------------------------------------------------------------------------
OPTIONS FOR REDEMPTION PROCEEDS
You may receive your redemption proceeds in one of three ways: check,exchange to
another Vanguard fund, or Fund Express Redemption.
- --------------------------------------------------------------------------------
CHECK REDEMPTIONS
Normally,  Vanguard  will  mail  your  check  within  two  business  days  of  a
redemption.
- --------------------------------------------------------------------------------
EXCHANGE REDEMPTIONS
As described  above, an exchange  involves using the proceeds of your redemption
to purchase shares of another Vanguard fund.
- --------------------------------------------------------------------------------
FUND EXPRESS REDEMPTIONS
Vanguard  will  electronically  transfer  funds to your  pre-linked  checking or
savings account.
- --------------------------------------------------------------------------------

FOR OUR MUTUAL PROTECTION
For your best interests and ours, Vanguard applies these additional requirements
to redemptions:

REQUEST IN "GOOD ORDER"
All redemption requests must be received by Vanguard in "good order." This means
that your request must include:
 o The Fund name and account number.
 o The amount of the transaction (in dollars or shares).
 o Signatures  of all  owners  exactly as  registered  on the  account (for mail
   requests).
 o Signature guarantees (if  required).*
 o Any supporting legal documentation that may be required.
 o Any outstanding certificates representing shares to be redeemed.

*For instance,  a signature guarantee must be provided by all registered account
 shareholders  when redemption  proceeds are to be sent to a different person or
 address. A signature guarantee can be obtained from most commercial and savings
 banks,credit unions, trust companies, or member firms of a U.S. stock exchange.

TRANSACTIONS ARE PROCESSED AT THE NEXT-DETERMINED SHARE PRICE AFTER VANGUARD HAS
RECEIVED ALL REQUIRED INFORMATION.
<PAGE>
                                                                              21


- --------------------------------------------------------------------------------
LIMITS ON ACCOUNT ACTIVITY
Because  excessive account  transactions can disrupt  management of the Fund and
increase the Fund's costs for all shareholders, Vanguard limits account activity
as follows:
o    You may make no more than TWO  SUBSTANTIVE  "ROUND TRIPS"  THROUGH THE FUND
     during any 12-month period.
o    Your round trips through the Fund must be at least 30 days apart.
o    The Fund may refuse a share purchase at any time, for any reason.
o    Vanguard may revoke an investor's telephone exchange privilege at any time,
     for any reason.

A "round trip" is a redemption  from the Fund  followed by a purchase  back into
the  Fund.  Also,  a  "round  trip"  covers  transactions  accomplished  by  any
combination  of methods,  including  transactions  conducted by check,  wire, or
exchange to from another Vanguard fund. "Substantive" means a dollar amount that
Vanguard  determines,  in  its  sole  discretion,  could  adversely  affect  the
management of the Fund.
- --------------------------------------------------------------------------------
RETURN YOUR SHARE CERTIFICATES
Any portion of your account represented by share certificates cannot be redeemed
until you return the  certificates  to Vanguard.  Certificates  must be returned
(unsigned),  along with a letter  requesting  the sale or  exchange  you wish to
process, via certified mail to:

The Vanguard Group
455 Devon Park Drive
Wayne, PA 19087-1815
- --------------------------------------------------------------------------------
ALL TRADES ARE FINAL
Vanguard  will not cancel any  transaction  request  (including  any purchase or
redemption)  that we believe to be authentic once the request has been initiated
and a confirmation number assigned.
- --------------------------------------------------------------------------------
UNCASHED CHECKS
Please cash your distribution or redemption  checks promptly.  Vanguard will not
pay interest on uncashed checks.
- --------------------------------------------------------------------------------

TRANSFERRING REGISTRATION
You can  transfer  the  registration  of your Fund  shares to  another  owner by
completing a transfer form and sending it to Vanguard.

First-class mail to:            Express or Registered mail to:
The Vanguard Group              The Vanguard Group
P.O. Box 1110                   455 Devon Park Drive
Valley Forge, PA 19482-1110     Wayne, PA 19087-1815

For clients of Vanguard's Institutional Division . . .

First-class mail to:            Express or Registered mail to:
The Vanguard Group              The Vanguard Group
P.O. Box 2900                   455 Devon Park Drive
Valley Forge, PA 19482-2900     Wayne, PA 19087-1815
- --------------------------------------------------------------------------------
<PAGE>
22

FUND AND ACCOUNT UPDATES

STATEMENTS AND REPORTS
We will send you account and tax  statements to help you keep track of your Fund
account  throughout  the year as well as when you are preparing  your income tax
returns.
     In addition,  you will  receive  financial  reports  about the Fund twice a
year.  These   comprehensive   reports  include  an  assessment  of  the  Fund's
performance  (and a comparison  to its industry  benchmark),  an overview of the
financial  markets,  a  report  from  the  advisers,  and the  Fund's  financial
statements which include a listing of the Fund's holdings.
     To keep  the  Fund's  costs  as low as  possible  (so  that  you and  other
shareholders can keep more of the Fund's investment earnings), Vanguard attempts
to  eliminate  duplicate  mailings  to the same  address.  When two or more Fund
shareholders  have the same last name and address,  we send just one Fund report
to that address--instead of mailing separate reports to each shareholder. If you
want us to send  separate  reports,  notify our Client  Services  Department  at
1-800-662-2739.
- --------------------------------------------------------------------------------
CONFIRMATION STATEMENT
Sent each time you buy,  sell, or exchange  shares;  confirms the trade date and
the amount of your transaction.
- --------------------------------------------------------------------------------
PORTFOLIO SUMMARY [BOOK]
Mailed quarterly for most accounts;  shows  the market  value of your account at
the close of the statement period, as well as distributions,  purchases,  sales,
and exchanges for the current calendar year.
- --------------------------------------------------------------------------------
FUND FINANCIAL REPORTS
Mailed in December and June for this Fund.
- --------------------------------------------------------------------------------
TAX STATEMENTS
Generally mailed in January;  report previous year's  dividend and capital gains
distributions,  proceeds from the sale of shares, and distributions from IRAs or
other retirement accounts.
- --------------------------------------------------------------------------------
AVERAGE COST REVIEW STATEMENT [BOOK]
Issued quarterly for most taxable accounts (accompanies your Portfolio Summary);
shows the average  cost of shares that you redeemed  during the  calendar  year,
using only the average cost single category method.
- --------------------------------------------------------------------------------
<PAGE>

                     (THIS PAGE INTENTIONALLY LEFT BLANK.)

<PAGE>

                     (THIS PAGE INTENTIONALLY LEFT BLANK.)

<PAGE>

GLOSSARY OF INVESTMENT TERMS

ACTIVE MANAGEMENT
An investment approach that seeks to exceed the average returns of the financial
markets.  Active  managers  rely on research,  market  forecasts,  and their own
judgment and experience in selecting securities to buy and sell.

BOND
A debt security (IOU) issued by a corporation,  government, or government agency
in exchange for the money you lend it. In most  instances,  the issuer agrees to
pay back the loan by a specific date and to make regular interest payments until
that date.

CAPITAL GAINS DISTRIBUTION
Payment to mutual fund  shareholders  of gains  realized on securities  that the
fund has sold at a profit, minus any realized losses.

CASH RESERVES
Cash deposits,  short-term  bank deposits,  and money market  instruments  which
include U.S.  Treasury bills,  bank  certificates  of deposit (CDs),  repurchase
agreements, commercial paper, and banker's acceptances.

COMMON STOCK
A security  representing  ownership  rights in a  corporation.  A stockholder is
entitled  to share in the  company's  profits,  some of which may be paid out as
dividends.

DIVIDEND INCOME
Payment to  shareholders  of income from  interest or  dividends  generated by a
fund's investments.

EXPENSE RATIO
The  percentage  of a fund's  average net assets used to pay its  expenses.  The
expense ratio  includes  management  fees,  administrative  fees,  and any 12b-1
distribution fees.

FUND DIVERSIFICATION
Holding a variety of securities so that a fund's return is not badly hurt by the
poor performance of a single security, industry, or country.

INDEX
An unmanaged group of securities whose overall performance is used as a standard
to measure investment performance.

INVESTMENT ADVISER
An  organization  that  makes  the  day-to-day   decisions  regarding  a  fund's
investments.

NET ASSET VALUE (NAV)
The market value of a mutual fund's total assets, minus liabilities,  divided by
the  number of shares  outstanding.  The value of a single  share is called  its
share value or share price.

PASSIVE MANAGEMENT
A low-cost  investment strategy in which a mutual fund attempts to match--rather
than  outperform--a  particular  stock  or bond  market  index.  Also  known  as
indexing.

TOTAL RETURN
A percentage change,  over a specified time period, in a mutual fund's net asset
value,  with the ending net asset value adjusted to account for the reinvestment
of all distributions of dividends and capital gains.

VOLATILITY
The  fluctuations  in value of a mutual  fund or other  security.  The greater a
fund's volatility, the wider the fluctuations between its high and low prices.

YIELD
Income  (interest  or  dividends)  earned  by  an  investment,  expressed  as  a
percentage of the investment's price.

<PAGE>

[SHIP LOGO]
[THE VANGUARD GROUP (R) LOGO]
Post Office Box 2600
Valley Forge, PA 19482-2600

FOR MORE INFORMATION
If you'd  like more  information  about  Vanguard  Asset  Allocation  Fund,  the
following documents are available free upon request:

ANNUAL/SEMIANNUAL REPORT TO SHAREHOLDERS
Additional  information about the Fund's  investments is available in the Fund's
annual and semiannual reports to shareholders. In these reports, you will find a
discussion of the market conditions and investment strategies that significantly
affected the Fund's performance during the most recent fiscal year.

STATEMENT  OF  ADDITIONAL  INFORMATION  (SAI)
The SAI  provides  more  detailed information about the Fund.

The  current  annual and  semiannual  reports  and the SAI are  incorporated  by
reference into (and are thus legally a part of) this prospectus.

To receive a free copy of the latest annual or semiannual  report or the SAI, or
to request additional information about the Fund or other Vanguard funds, please
contact us as follows:

THE VANGUARD GROUP
INVESTOR INFORMATION DEPARTMENT
P.O. BOX 2600
VALLEY FORGE, PA 19482-2600

TELEPHONE:
1-800-662-7447 (SHIP)

TEXT TELEPHONE:
1-800-952-3335

WORLD WIDE WEB:
WWW.VANGUARD.COM

If you are a current  Fund  shareholder  and would like  information  about your
account, account transactions, and/or account statements, please call:

CLIENT SERVICES DEPARTMENT
TELEPHONE:
1-800-662-2739 (CREW)


TEXT TELEPHONE:
1-800-749-7273


INFORMATION  PROVIDED BY THE  SECURITIES AND EXCHANGE  COMMISSION  (SEC)

You can review and copy  information  about the Fund  (including the SAI) at the
SEC's  Public  Reference  Room in  Washington,  DC. To find out more  about this
public service,  call the SEC at  1-800-SEC-0330.  Reports and other information
about the Fund are also available on the SEC's website (www.sec.gov), or you can
receive copies of this  information,  for a fee, by writing the Public Reference
Section, Securities and Exchange Commission, Washington, DC 20549-6009.

Fund's Investment Company Act file number: 811-5628

(C) 2000 The Vanguard Group, Inc.
All rights reserved.
Vanguard Marketing Corporation,
Distributor.

P078N-01/21/2000

<PAGE>
VANGUARD(R)
ASSET ALLOCATION
FUND

Participant Prospectus
January 21, 2000

This  prospectus  contains  financial  data for the Fund through the fiscal year
ended September 30, 1999.

[SHIP GRAPHIC]
[A MEMBER OF THE VANGUARD GROUP(R) LOGO]
<PAGE>


VANGUARD ASSET ALLOCATION FUND
Participant Prospectus
January 21, 2000

An Asset Allocation Mutual Fund

- --------------------------------------------------------------------------------
   CONTENTS
- --------------------------------------------------------------------------------
 1 FUND PROFILE                        10 DIVIDENDS, CAPITAL GAINS, AND TAXES

 3 ADDITIONAL INFORMATION              11 SHARE PRICE

 3 A WORD ABOUT RISK                   12 FINANCIAL HIGHLIGHTS

 3 WHO SHOULD INVEST                   14 INVESTING WITH VANGUARD

 4 PRIMARY INVESTMENT STRATEGIES       15 ACCESSING FUND INFORMATION BY COMPUTER

 9 THE FUND AND VANGUARD               GLOSSARY (inside back cover)

 9 INVESTMENT ADVISER
- --------------------------------------------------------------------------------

- --------------------------------------------------------------------------------
 WHY READING THIS PROSPECTUS IS IMPORTANT
 This prospectus explains the objective, risks, and strategies of Vanguard Asset
 Allocation  Fund.  To  highlight  terms and  concepts  important to mutual fund
 investors,  we have  provided  "Plain  Talk (R) "  explanations  along the way.
 Reading the  prospectus  will help you to decide  whether the Fund is the right
 investment for you. We suggest that you keep it for future reference.
- --------------------------------------------------------------------------------
- --------------------------------------------------------------------------------
 IMPORTANT NOTE
 This prospectus is intended for participants in  employer-sponsored  retirement
 or savings plans.  Another version -- for  investors  who would like to  open a
 personal investment account --can be obtained by calling Vanguard at 1-800-662-
 7447.
- -------------------------------------------------------------------------------
NEITHER  THE  SECURITIES  AND  EXCHANGE  COMMISSION  NOR  ANY  STATE  SECURITIES
COMMISSION HAS APPROVED OR  DISAPPROVED  OF THESE  SECURITIES OR PASSED UPON THE
ACCURACY OR ADEQUACY OF THIS PROSPECTUS. ANY REPRESENTATION TO THE CONTRARY IS A
CRIMINAL OFFENSE.

<PAGE>
                                                                               1

FUND PROFILE

The following profile summarizes key features of Vanguard Asset Allocation Fund.

INVESTMENT OBJECTIVE
The Fund seeks to provide  maximum  long-term  total return (capital change plus
income) while  incurring  less stock market risk than a fund made up entirely of
stocks.

INVESTMENT STRATEGIES
The Fund  invests in common  stocks,  bonds,  and money  market  instruments  in
proportions  consistent  with their expected  returns and risks, as evaluated by
the Fund's  adviser.  These  proportions are changed from time to time as market
expectations  shift. The Fund is permitted to be 100% invested in any one of the
three asset classes.

PRIMARY RISKS
THE FUND'S TOTAL RETURN,  LIKE STOCK AND BOND PRICES  GENERALLY,  WILL FLUCTUATE
WITHIN A WIDE  RANGE,  SO AN  INVESTOR  COULD LOSE MONEY OVER SHORT OR EVEN LONG
PERIODS.  The Fund is also subject to:
o    Interest  rate risk,  which is the chance  that bond  prices  overall  will
     decline over short or even long periods due to rising interest rates.
o    Manager risk,  which is the chance that poor security  selection will cause
     the Fund to underperform other funds with similar investment objectives.

PERFORMANCE/RISK INFORMATION
The bar chart and table below  provide an indication of the risk of investing in
the Fund. The bar chart shows the Fund's  performance in each calendar year over
a ten-year  period.  The table shows how the Fund's average annual total returns
for one, five, and ten calendar years compare with those of a broad-based market
index and a composite index.  Keep in mind that the Fund's past performance does
not indicate how it will perform in the future.


              ----------------------------------------------------
                              ANNUAL TOTAL RETURNS
              ----------------------------------------------------
                                 [BAR CHART]
                    1990  0.89%         1995 35.46%
                    1991 25.59%         1996 15.73%
                    1992  7.51%         1997 27.32%
                    1993 13.49%         1998 25.40%
                    1994 -2.32%         1999  5.21%
              ----------------------------------------------------
     During the period shown in the bar chart, the highest return for a calendar
quarter was 14.31% (quarter ended December 31, 1998) and the lowest return for a
quarter was -8.31% (quarter ended March 31, 1990).

<PAGE>
2
- --------------------------------------------------------------------------------
          AVERAGE ANNUAL TOTAL RETURNS FOR YEARS ENDED DECEMBER 31, 1999
- --------------------------------------------------------------------------------
                                      1 YEAR          5 YEARS        10 YEARS
- --------------------------------------------------------------------------------
Vanguard Asset Allocation Fund          5.21%         21.37%            14.80%
S&P 500 Index                          21.04          28.56             18.21
Composite Index*                        9.90          21.70             14.95
- --------------------------------------------------------------------------------
*Weighted 65% in the S&P 500 Index, 35% in the Lehman Brothers Long U.S.Treasury
 Bond Index.
- --------------------------------------------------------------------------------

FEES AND EXPENSES
The following table describes the fees and expenses you would pay if you buy and
hold shares of the Fund. The expenses shown under Annual Fund Operating Expenses
are based upon those incurred in the fiscal year ended September 30, 1999.

      SHAREHOLDER FEES (fees paid directly from your investment)
      Sales Charge (Load) Imposed on Purchases:                          None
      Sales Charge (Load) Imposed on Reinvested Dividends:               None
      Redemption Fee:                                                    None
      Exchange Fee:                                                      None

      ANNUAL FUND OPERATING EXPENSES (expenses deducted from the Fund's assets)
      Management Expenses:                                               0.47%
      12b-1 Distribution Fee:                                            None
      Other Expenses:                                                    0.02%
       TOTAL ANNUAL FUND OPERATING EXPENSE S:                            0.49%


 The following  example is intended to help you compare the cost of investing in
the Fund with the cost of investing in other mutual funds.  It  illustrates  the
hypothetical  expenses  that you would incur over various  periods if you invest
$10,000 in the Fund.  This example assumes that the Fund provides a return of 5%
a year, and that operating  expenses  remain the same. The results apply whether
or not you redeem your investment at the end of each period.

               -------------------------------------------------
                 1 YEAR      3 YEARS      5 YEARS      10 YEARS
               -------------------------------------------------
                   $50         $157         $274          $616
               -------------------------------------------------


  THIS EXAMPLE SHOULD NOT BE CONSIDERED TO REPRESENT ACTUAL PERFORMANCE FROM THE
PAST OR FOR THE FUTURE. ACTUAL FUTURE EXPENSES MAY BE HIGHER OR LOWER THAN THOSE
SHOWN.
- --------------------------------------------------------------------------------
                               PLAIN TALK ABOUT
                                 FUND EXPENSES
All mutual funds have operating  expenses.  These  expenses,  which are deducted
from a fund's gross  income,  are expressed as a percentage of the net assets of
the fund. Vanguard Asset Allocation Fund's expense ratio in fiscal year 1999 was
0.49%,  or $4.90 per $1,000 of average net assets.  The average  flexible mutual
fund had  expenses in 1998 of 1.41%,  or $14.10 per $1,000 of average net assets
(derived  from data  provided by Lipper Inc.,  which  reports on the mutual fund
industry).
- --------------------------------------------------------------------------------
<PAGE>

                                                                               3

- --------------------------------------------------------------------------------
                               PLAIN TALK ABOUT
                            THE COSTS OF INVESTING
 Costs are an important  consideration in choosing a mutual fund. That's because
 you, as a shareholder,  pay the costs of operating a fund, plus any transaction
 costs associated with the fund's buying and selling of securities.  These costs
 can erode a substantial  portion of the gross income or capital  appreciation a
 fund  achieves.  Even seemingly  small  differences in expenses can, over time,
 have a dramatic effect on a fund's performance.
- --------------------------------------------------------------------------------

- --------------------------------------------------------------------------------
ADDITIONAL INFORMATION

DIVIDENDS AND CAPITAL GAINS                           NEWSPAPER ABBREVIATION
Dividends are distributed in June and December;       AssetA
capital gains, if any, are distributed in December
                                                      VANGUARD FUND NUMBER
INVESTMENT ADVISER                                    078
Mellon Capital Management Corporation, San
Francisco, Calif., since inception                    CUSIP NUMBER
                                                      922020102
INCEPTION DATE
November 3, 1988                                      TICKER SYMBOL
                                                      VAAPX
NET ASSETS AS OF SEPTEMBER 30, 1999
$8.18 billion
- --------------------------------------------------------------------------------

================================================================================
A WORD ABOUT RISK

This prospectus  describes risks you would face as an investor in Vanguard Asset
Allocation  Fund.  It is  important  to keep in mind one of the main  axioms  of
investing: The higher the risk of losing money, the higher the potential reward.
The  reverse,  also,  is  generally  true:  The lower  the  risk,  the lower the
potential  reward.  As you consider an investment in Vanguard  Asset  Allocation
Fund,  you should also take into account your  personal  tolerance for the daily
fluctuations of the stock market.
     Look for this [FLAG ICON] symbol  throughout the prospectus.  It is used to
mark detailed  information  about each type of risk that you would confront as a
shareholder of the Fund.
================================================================================

WHO SHOULD INVEST
The Fund may be a suitable investment for you if:
o    You wish to  invest in a fund that  actively  manages a mix of U.S.  common
     stocks, bonds, and money market instruments.
o    You are seeking growth of capital over the long term--at least five years.
o    You are not looking for current income.

 THE VANGUARD FUNDS DO NOT PERMIT MARKET-TIMING. DO NOT INVEST IN THIS FUND IF
YOU ARE A MARKET-TIMER.

<PAGE>

4
- --------------------------------------------------------------------------------
                               PLAIN TALK ABOUT
                            COSTS AND MARKET-TIMING
 Some  investors  try  to  profit  from   market-timing--switching   money  into
 investments  when they expect  prices to rise,  and taking  money out when they
 expect  the  market to fall.  As money is  shifted  in and out,  a fund  incurs
 expenses for buying and selling  securities.  These costs are borne by all fund
 shareholders,  including the long-term investors who do not generate the costs.
 Therefore,  the Fund  discourages  short-term  trading by, among other  things,
 limiting the number of exchanges it permits.
- --------------------------------------------------------------------------------

     The Fund has adopted the following  policies,  among others,  to discourage
short-term trading:
o    The Fund  reserves  the right to  reject  any  purchase  request--including
     exchanges from other  Vanguard  funds--that it regards as disruptive to the
     efficient  management  of the Fund.  A purchase  request  could be rejected
     because  of the  timing  of the  investment  or  because  of a  history  of
     excessive trading by the investor.
o    There is a limit on the  number of times you can  exchange  into and out of
     the Fund (see "Redeeming Shares" in the INVESTING WITH VANGUARD section).
o    The Fund reserves the right to stop offering shares at any time.

PRIMARY INVESTMENT STRATEGIES
This section explains the strategies that the investment adviser uses in pursuit
of the  Fund's  objective,  long-term  growth of  capital  and  income.  It also
explains how the adviser implements these strategies.  In addition, this section
discusses several important  risks--market risk, interest rate risk, and manager
risk--faced by investors in the Fund. The Fund's Board of Trustees  oversees the
management of the Fund, and may change the investment strategies in the interest
of  shareholders.  Note  that  the  investment  objective  of  the  Fund  is not
fundamental, and may be changed without a shareholder vote.


MARKET EXPOSURE
The adviser, Mellon Capital Management Corporation,  allocates the Fund's assets
among stocks,  bonds, and money market instruments in proportions that depend on
projected returns and risks for each asset class.

STOCKS
A portion of the Fund's assets is typically invested in common stocks.

[FLAG] THE FUND IS SUBJECT TO STOCK MARKET RISK,  WHICH IS THE POSSIBILITY  THAT
     STOCK PRICES  OVERALL WILL DECLINE OVER SHORT OR EVEN LONG  PERIODS.  STOCK
     MARKETS TEND TO MOVE IN CYCLES,  WITH PERIODS OF RISING  PRICES AND PERIODS
     OF FALLING PRICES.

 The Fund  will  typically  hold a  diversified  combination  of  common  stocks
intended to parallel the performance of the S&P 500 Index, which is dominated by
large-capitalization   stocks.  The  stocks  are  evaluated  using  a  "dividend
discount" model.  This model provides an estimate of the total return of the S&P
500 Index,  based upon the  expected  earnings of each of the  companies  in the
index.

<PAGE>

                                                                               5

     To illustrate the volatility of stock prices, the following table shows the
best,  worst,  and average total returns for the U.S.  stock market over various
periods as measured by the Standard & Poor's 500 Index,  a widely used barometer
of market  activity.  (Total returns  consist of dividend  income plus change in
market  price.)  Note that the returns  shown do not include the costs of buying
and selling  stocks or other  expenses  that a real-world  investment  portfolio
would  incur.  Note,  also,  that the gap between best and worst tends to narrow
over the long term.

- --------------------------------------------------------------------------------
                      U.S. STOCK MARKET RETURNS (1926-1999)
- --------------------------------------------------------------------------------
                         1 YEAR         5 YEARS        10 YEARS       20 YEARS
- --------------------------------------------------------------------------------
Best                      54.2%           24.1%          19.9%          17.7%
Worst                    -43.1           -12.4           -0.8            3.1
Average                   13.1            10.7           11.0           11.0
- --------------------------------------------------------------------------------
     The table  covers all of the 1-, 5-,  10-,  and 20-year  periods  from 1926
through 1998. You can see, for example,  that while the average return on stocks
for all of the 5-year periods was 10.7%,  returns for individual  5-year periods
ranged  from a -12.4%  average  (from  1928  through  1932) to 24.1%  (from 1994
through 1998).  These average returns reflect past performance on common stocks;
you should not regard them as an  indication  of future  returns from either the
stock market as a whole or this Fund in particular.


BONDS
A portion of the Fund's assets is typically invested in bonds.

[FLAG] THE FUND IS SUBJECT TO INTEREST RATE RISK,  WHICH IS THE POSSIBILITY THAT
     BOND PRICES  OVERALL  WILL  DECLINE  OVER SHORT OR EVEN LONG PERIODS DUE TO
     RISING INTEREST RATES.

 Although bonds are often thought to be less risky than stocks,  there have been
periods when bond prices have fallen significantly due to rising interest rates.
For instance, prices of long-term bonds fell by almost 48% between December 1976
and September 1981.

- --------------------------------------------------------------------------------
                               PLAIN TALK ABOUT
                           BONDS AND INTEREST RATES
As a rule,  when  interest  rates rise,  bond prices fall.  The opposite is also
true:  Bond  prices go up when  interest  rates  fall.  Why do bond  prices  and
interest  rates move in opposite  directions?  Let's assume that you hold a bond
offering a 5% yield. A year later,  interest rates are on the rise and bonds are
offered with a 6% yield. With  higher-yielding  bonds available,  you would have
trouble selling your 5% bond for the price you  paid--causing  you to lower your
asking  price.  On the other hand,  if interest  rates were falling and 4% bonds
were  being  offered,  you should be able to sell your 5% bond for more than you
paid.
- --------------------------------------------------------------------------------
     To illustrate the relationship  between bond prices and interest rates, the
following  table shows the effect of a 1% and a 2% change  (both up and down) in
interest rates on three bonds of different maturities, each with a face value of
$1,000.

<PAGE>
6
<TABLE>
<CAPTION>
- ------------------------------------------------------------------------------------------------------------
                             HOW INTEREST RATE CHANGES AFFECT BONDS*
- ------------------------------------------------------------------------------------------------------------
                              VALUE OF A $1,000   VALUE OF A $1,000   VALUE OF A $1,000    VALUE OF A $1,000
                              BOND AFTER A 2%     BOND AFTER A 2%     BOND AFTER A 1%      BOND AFTER A 1%
                                 INCREASE            DECREASE            INCREASE             DECREASE
TYPE OF BOND (MATURITY)       IN INTEREST RATES   IN INTEREST RATES   IN INTEREST RATES    IN INTEREST RATES
- ------------------------------------------------------------------------------------------------------------
<S>                                 <C>               <C>                 <C>                  <C>
Short-Term (2.5 years)              $978              $1,023               $956                $1,046
Intermediate-Term (10 years)         932               1,074                870                 1,156
Long-Term (20 years)                 901               1,116                816                 1,251
- ------------------------------------------------------------------------------------------------------------
*Assuming a 7% yield.
- ------------------------------------------------------------------------------------------------------------
</TABLE>


     The  Fund  will  typically  invest  its  allocation  to  bonds in a pool of
long-term U.S. Treasury bonds,  which mature in 10 to 30 years. It may also hold
other "full faith and credit" obligations of the U.S. government.

     The U.S. government guarantees the timely payment of interest and principal
for its Treasury  bonds,  but does not  guarantee  its bonds'  prices.  In other
words, while Treasury bonds enjoy the highest credit ratings, their prices--like
the prices of other bonds in the  Fund--will  fluctuate with changes in interest
rates.
     The  adviser  evaluates  bonds'  attractiveness  based upon  their  current
yield-to-maturity,  which is an estimate of total return that considers a bond's
purchase price,  redemption  value,  time to maturity,  yield,  and time between
interest payments.

- --------------------------------------------------------------------------------
                               PLAIN TALK ABOUT
                                TYPES OF BONDS
Bonds are issued (sold) by many sources: Corporations issue corporate bonds; the
federal  government  issues  U.S.  Treasury  bonds;   agencies  of  the  federal
government  issue agency bonds;  and mortgage  holders  issue  "mortgage-backed"
bonds,  such as those of the Government  National Mortgage  Association  (GNMA).
Each issuer is  responsible  for paying back the bond's initial value as well as
making periodic interest payments.

- --------------------------------------------------------------------------------
- --------------------------------------------------------------------------------
                                PLAIN TALK ABOUT
                                BOND MATURITIES
 A bond is issued with a specific maturity  date--the date when the bond issuer,
 or seller,  must pay back the bond's initial value (known as its "face value").
 Bond  maturities  generally  range from less than one year  (short-term)  to 30
 years (long-term).  The longer a bond's maturity,  the more risk you, as a bond
 investor,  face as interest  rates  rise--but  also the more interest you could
 receive.  Long-term  bonds are more  suitable  for  investors  willing  to take
 greater risks in hope of higher yields;  short-term  bond  investors  should be
 willing to accept lower yields in return for less  fluctuation  in the value of
 their investment.
- --------------------------------------------------------------------------------

SECURITY SELECTION
Mellon Capital  Management  Corporation  (Mellon Capital),  adviser to the Fund,
makes no  effort  to  choose  among  individual  stocks  or  bonds  to  identify
attractive securities. Rather, the adviser tries to determine the mix of stocks,
bonds,  and  money  market  instruments  that  offers  the best  combination  of
potential  return and risk. The aim is to maximize the long-term total return of
the Fund  while  incurring  less  stock  market  risk than a  portfolio

<PAGE>

                                                                               7

made up entirely of stocks.  At any given time, Mellon Capital may allocate all,
a portion,  ornone of the Fund's  assets to  large-capitalization  U.S.  stocks,
long-term U.S. Treasury bonds, or cash reserves.
     For the Fund's  common stock  allocation,  the adviser  uses a  diversified
portfolio of stocks selected to parallel the performance of the S&P 500 Index or
S&P 500 stock index futures.  For the Fund's bond  allocation,  the adviser uses
long-term (10- to 30-year  maturities) U.S.  Treasury bonds and/or U.S. Treasury
Bond futures  and/or U.S.  Treasury Note  futures.  For the Fund's cash reserves
allocation, the adviser can use a variety of money market instruments, including
U.S.  Treasury bills,  government  agency  securities,  high-quality  commercial
paper, and certificates of deposit.
     Mellon  Capital  uses a computer  model to estimate  return and risk and to
recommend  shifts in  allocations.  The  adviser  implements  these  shifts in a
disciplined  manner.  The adviser believes that,  within the fluctuations of the
financial markets, there are occasional brief periods in which the market values
of the asset  classes do not  reflect  their true  value.  The Fund  attempts to
capitalize  on these  perceived  imbalances  by  changing  the mix of the Fund's
holdings in the three asset  classes.  There are no limitations on the amount of
the Fund's  assets  that may be  allocated  to stocks,  bonds,  or money  market
instruments; it can be 100% invested in any of the three asset classes.
     The Fund is generally managed without regard to tax ramifications.

[FLAG] THE FUND IS SUBJECT TO MANAGER RISK,  WHICH IS THE  POSSIBILITY  THAT THE
     ADVISER MAY DO A POOR JOB  ALLOCATING  THE FUND'S NET ASSETS AMONG  STOCKS,
     BONDS, AND MONEY MARKET INSTRUMENTS.

     Since the Fund's asset allocation changes according to the adviser's timely
projection  of risk and return,  the Fund may  exhibit  higher  volatility  than
balanced funds with static allocations.
     Historical  evidence indicates that correctly timing portfolio  allocations
among asset classes has been a difficult strategy to implement successfully on a
consistent  basis.  Although Mellon Capital has substantial  experience in asset
allocation,  there  can be no  assurance  that  the  adviser  will  consistently
anticipate which asset class will perform best in the future.
     The Fund's investment  results could suffer,  for example,  if only a small
portion of the Fund's assets were allocated to stocks during a significant stock
market  advance,  or if a major  portion of its assets were  allocated to stocks
during a market decline.  Similarly,  the Fund's short-term  investment  results
could also  suffer if the Fund were  substantially  invested  in bonds at a time
when interest rates increased.


TURNOVER RATE
Although the Fund  generally  seeks to invest for the long term,  it retains the
right to sell  securities  regardless of how long the securities have been held.
The Fund's average  turnover rate for the past five years has been about 32%. (A
turnover  rate of 100% would occur,  for example,  if the Fund sold and replaced
securities valued at 100% of its net assets within a one-year period.)
<PAGE>
8
- --------------------------------------------------------------------------------
                               PLAIN TALK ABOUT
                                 TURNOVER RATE

Before  investing in a mutual fund,  you should review its turnover  rate.  This
gives an  indication  of how  transaction  costs could affect the fund's  future
returns.  In general,  the greater the volume of buying and selling by the fund,
the greater the impact that brokerage  commissions and other  transaction  costs
will have on its return. Also, funds with high turnover rates may be more likely
to generate  capital gains that must be  distributed to  shareholders  as income
subject to taxes.  As of September 30, 1999,  the average  turnover rate for all
asset allocation funds was approximately 95%, according to Morningstar, Inc.

- --------------------------------------------------------------------------------
- --------------------------------------------------------------------------------
                                PLAIN TALK ABOUT
                                  DERIVATIVES
 A  derivative  is a financial  contract  whose value is based on (or  "derived"
 from) a traditional  security (such as a stock or a bond),  an asset (such as a
 commodity  like gold),  or a market index (such as the S&P 500 Index).  Futures
 and options are derivatives  that have been trading on regulated  exchanges for
 more  than  two  decades.  These  "traditional"  derivatives  are  standardized
 contracts  that can  easily be bought  and sold,  and whose  market  values are
 determined and published daily. It is these  characteristics that differentiate
 futures and options from the relatively new types of  derivatives.  If used for
 speculation or as leveraged  investments,  derivatives  can carry  considerable
 risks.
- --------------------------------------------------------------------------------

OTHER INVESTMENT POLICIES AND RISKS
Besides  investing in common stocks,  bonds, and money market  instruments,  the
Fund may make certain other kinds of investments to achieve its objective.
     The Fund may invest, to a limited extent, in foreign securities.
     The Fund may also invest in stock and bond  futures and options  contracts,
which are traditional  types of  derivatives.  Under normal  circumstances,  the
market  value of these  contracts  and  options may  represent  up to 50% of the
Fund's assets. (Under unusual circumstances,  the Fund may hold futures equal in
value to 100% of its net assets.)
     Losses (or gains) involving futures can sometimes be  substantial--in  part
because a relatively small price movement in a futures contract may result in an
immediate  and  substantial  loss (or gain)  for a fund.  This Fund will not use
futures for speculative  purposes.  The Fund will keep separate cash reserves or
short-term,   cash-equivalent   securities  in  the  amount  of  the  obligation
underlying the futures contract.
     The reasons for which the Fund will invest in futures and options are:
o    To hedge dividend accruals.
o    To keep cash on hand to meet  shareholder  redemptions or other needs while
     simulating full investment in stocks or bonds.
o    To reduce the Fund's  transaction costs or add value when these instruments
     are favorably priced.
o    To use as an investment tool when reallocating assets among stocks,  bonds,
     and  money  market  instruments.  For  example,  the  adviser  may  wish to
     reallocate 10% of the Fund's assets from stocks to bonds. To implement this
     change rapidly and with low transaction  costs,  the adviser may sell stock
     index futures and purchase bond index futures.
<PAGE>
                                                                               9

     The Fund may temporarily  depart from its normal  investment  policies--for
instance,   by  investing   substantially  in  cash  reserves--in   response  to
extraordinary market, economic, political, or other conditions. In doing so, the
Fund may succeed in avoiding losses but otherwise fail to achieve its investment
objective.


THE FUND AND VANGUARD

The Fund is a member of The Vanguard  Group, a family of more than 35 investment
companies  with more than 100 funds holding assets worth more than $530 billion.
All of the  Vanguard  funds  share  in the  expenses  associated  with  business
operations, such as personnel, office space, equipment, and advertising.

     Vanguard  also  provides   marketing   services  to  the  funds.   Although
shareholders do not pay sales commissions or 12b-1  distribution fees, each fund
pays its allocated share of The Vanguard Group's marketing costs.

- --------------------------------------------------------------------------------
                               PLAIN TALK ABOUT
                     VANGUARD'S UNIQUE CORPORATE STRUCTURE
 The Vanguard  Group is truly a MUTUAL mutual fund company.  It is owned jointly
 by the funds it  oversees  and thus  indirectly  by the  shareholders  in those
 funds. Most other mutual funds are operated by for-profit  management companies
 that may be owned by one person, by a group of individuals, or by investors who
 own the management company's stock. By contrast, Vanguard provides its services
 on an "at-cost"  basis, and the funds' expense ratios reflect only these costs.
 No separate  management  company reaps profits or absorbs losses from operating
 the funds.
- --------------------------------------------------------------------------------

INVESTMENT ADVISER
The Fund employs Mellon Capital  Management  Corporation,  595 Market St., Suite
3000, San Francisco,  CA 94105, as its investment  adviser.  Mellon Capital is a
wholly owned subsidiary of MBC Investment Corporation,  which itself is a wholly
owned subsidiary of Mellon Financial Corporation. Mellon Capital manages the
Fund subject to the control of the Trustees and officers of the Fund.
     Mellon  Capital's  advisory fee is paid at the end of each fiscal  quarter.
This fee is based on  certain  annual  percentage  rates  applied  to the Fund's
average  month-end  assets  for each  quarter.  In  addition,  Mellon  Capital's
advisory fee is  increased  or  decreased,  based on the  cumulative  investment
performance  of the Fund over a trailing  36-month  period as compared  with the
cumulative  total return of the Asset  Allocation  Composite  Index (65% S&P 500
Index; 35% Lehman Brothers Long U.S. Treasury Bond Index) over the same period.

     For the fiscalyear  ended  September 30, 1999, the investment  advisory fee
paid to Mellon  Capital  represented  an  effective  annual rate of 0.11% of the
Fund's average net assets before a decrease of 0.02% based on performance.

     The Fund has  authorized  Mellon  Capital  to choose  brokers or dealers to
handle the purchase and sale of securities  for the Fund,  and to seek to obtain
the best available  price and most  favorable  execution from these brokers with
respect to all transactions.
     In the interest of obtaining  better  execution  of a  transaction,  Mellon
Capital  may choose  brokers  who charge  higher  commissions.  If more than one
broker can obtain the best


<PAGE>
10

available  price and most  favorable  execution  of a  transaction,  then Mellon
Capital is  authorized  to choose a broker who, in  addition  to  executing  the
transaction, will provide research services to Mellon Capital or the Fund. Also,
the Fund may direct  Mellon  Capital  to use a  particular  broker  for  certain
transactions in exchange for commission rebates or research services provided to
the Fund.
     The Board of Trustees may, without prior approval from shareholders, change
the terms of an advisory agreement or hire a new investment adviser--either as a
replacement for an existing adviser or as an additional adviser. Any significant
change in the Fund's advisory  arrangements will be communicated to shareholders
in writing. In addition, as the Fund's sponsor and overall manager, The Vanguard
Group may provide investment advisory services to the Fund, on an at-cost basis,
at any time.

- --------------------------------------------------------------------------------
                               PLAIN TALK ABOUT
                              THE FUND'S ADVISER
Mellon Capital Management  Corporation is an investment advisory firm founded in
1983. As of September 30, 1999,  Mellon Capital managed more than $73 billion in
assets.  The managers  responsible for overseeing the  implementation  of Mellon
Capital's strategy for the Fund are:

WILLIAM L. FOUSE,  CFA,  Chairman  Emeritus of  Executive  Committee  for Mellon
Capital;  has worked in investment  management  since 1953;  with Mellon Capital
since its founding in 1983; B.A. and M.B.A.,  University of Kentucky.  Mr. Fouse
has managed the Fund since its inception in 1988.

THOMAS F. LOEB, Chairman,  Chief Executive Officer of Mellon Capital; has worked
in investment  management  since 1970; with Mellon Capital since its founding in
1983; B.A., Fairleigh Dickinson University;  M.B.A., University of Pennsylvania.
Mr. Loeb has managed the Fund since its inception in 1988.
- --------------------------------------------------------------------------------

DIVIDENDS, CAPITAL GAINS, AND TAXES

The Fund  distributes to shareholders  virtually all of its net income (interest
and dividends,  less  expenses),  as well as any capital gains realized from the
sale of its holdings.  Income  dividends  generally are  distributed in June and
December; capital gains distributions generally occur in December.
     Your  dividend  and  capital  gains  distributions  will be  reinvested  in
additional  Fund  shares  and  accumulate  on a  tax-deferred  basis  if you are
investing through an employer-sponsored retirement or savings plan. You will not
owe taxes on these  distributions until you begin withdrawals from the plan. You
should consult your plan administrator, your plan's Summary Plan Description, or
your tax adviser about the tax consequences of plan withdrawals.


<PAGE>

                                                                              11


- --------------------------------------------------------------------------------
                               PLAIN TALK ABOUT
                                 DISTRIBUTIONS
As a  shareholder,  you are  entitled  to your share of the fund's  income  from
interest and dividends, and gains from the sale of investments. You receive such
earnings as either an income  dividend or a capital gains  distribution.  Income
dividends come from both the dividends that the fund earns from its holdings and
the  interest it receives  from its money market and bond  investments.  Capital
gains are realized  whenever the fund sells securities for higher prices than it
paid for them. These capital gains are either short-term or long-term  depending
on whether the fund held the  securities  for one year or less, or more than one
year.
- --------------------------------------------------------------------------------

SHARE PRICE
The Fund's share price,  called its net asset value,  or NAV, is calculated each
business day after the close of trading on the New York Stock  Exchange (the NAV
is not  calculated  on holidays or other days when the Exchange is closed).  Net
asset  value per share is  computed  by adding up the total  value of the Fund's
investments and other assets,  subtracting any of its liabilities  (debts),  and
then dividing by the number of Fund shares outstanding:

        NET ASSET VALUE =      TOTAL ASSETS - LIABILITIES
                           -------------------------------
                              NUMBER OF SHARES OUTSTANDING

     Knowing the daily net asset value is useful to you as a shareholder because
it indicates the current value of your investment. The Fund's NAV, multiplied by
the  number of  shares  you own,  gives you the  dollar  amount  you would  have
received had you sold all of your shares back to the Fund that day.
     A NOTE ON PRICING:  The Fund's  investments  will be priced at their market
value when market  quotations are readily  available.  When these quotations are
not  readily  available,  investments  will  be  priced  at  their  fair  value,
calculated according to procedures adopted by the Fund's Board of Trustees.
     The Fund's  share price can be found  daily in the mutual fund  listings of
most major newspapers under the heading "Vanguard  Funds." Different  newspapers
use different abbreviations of the Fund's name, but the most common is ASSETA.

<PAGE>

12

FINANCIAL HIGHLIGHTS

The following financial  highlights table is intended to help you understand the
Fund's financial  performance for the past five years,  and certain  information
reflects  financial  results for a single Fund share.  The total  returns in the
table represent the rate that an investor would have earned or lost each year on
an investment  in the Fund  (assuming  reinvestment  of all dividend and capital
gains  distributions).  This  information  has been derived  from the  financial
statements audited by PricewaterhouseCoopers LLP, independent accountants, whose
report--along  with the Fund's financial  statements--is  included in the Fund's
most recent annual report to  shareholders.  You may have the annual report sent
to you without charge by contacting Vanguard.


<TABLE>
<CAPTION>

- ------------------------------------------------------------------------------------------
                                                   VANGUARD ASSET ALLOCATION FUND
                                                       YEAR ENDED SEPTEMBER 30,
                                       ---------------------------------------------------
                                             1999       1998      1997      1996      1995
- ------------------------------------------------------------------------------------------
<S>                                          <C>      <C>       <C>       <C>       <C>
NET ASSET VALUE, BEGINNING OF YEAR           $22.90   $21.53    $18.27    $17.03    $13.78
- ------------------------------------------------------------------------------------------
INVESTMENT OPERATIONS
Net Investment Income                           .80      .79       .74       .69       .64
Net Realized and Unrealized Gain (Loss)on
 Investments                                   2.50     2.33      4.29      1.82      3.18
                                       ---------------------------------------------------
 Total from Investment Operations              3.30     3.12      5.03      2.51      3.82
                                       ---------------------------------------------------
DISTRIBUTIONS
Dividends from Net Investment Income          (.91)    (.74)     (.72)     (.66)     (.57)
Distributions from Realized Capital Gains    (1.18)   (1.01)    (1.05)     (.61)       --
                                       ---------------------------------------------------
 Total Distributions                         (2.09)   (1.75)    (1.77)    (1.27)     (.57)
- ------------------------------------------------------------------------------------------
NET ASSET VALUE, END OF YEAR                 $24.11   $22.90    $21.53    $18.27    $17.03
==========================================================================================

TOTAL RETURN                                 14.68%   15.24%    29.42%    15.27%    28.57%
==========================================================================================

RATIOS/SUPPLEMENTAL DATA
Net Assets, End of Year (Millions)           $8,182   $5,637    $3,738    $2,341    $1,593
Ratio of Total Expenses to Average Net Assets 0.49%    0.49%     0.49%     0.47%     0.49%
Ratio of Net Investment Income to
 Average Net Assets                           3.49%    3.80%     3.96%     4.17%     4.41%
Turnover Rate                                   11%      60%       10%       47%       34%
==========================================================================================
</TABLE>

<PAGE>
                                                                              13
- --------------------------------------------------------------------------------
                               PLAIN TALK ABOUT
                  HOW TO READ THE FINANCIAL HIGHLIGHTS TABLE


The Fund began  fiscal 1999 with a net asset value  (price) of $22.90 per share.
During  the  year,  the Fund  earned  $0.80  per share  from  investment  income
(interest  and  dividends)  and  $2.50  per  share  from  investments  that  had
appreciated  in value or that were sold for higher prices than the Fund paid for
them.

Shareholders  received $2.09 per share in the form of dividend and capital gains
distributions.  A portion of each year's  distributions  may come from the prior
year's income or capital gains.

The  earnings  ($3.30  per  share)  minus the  distributions  ($2.09  per share)
resulted in a share price of $24.11 at the end of the year. This was an increase
of $1.21 per share (from  $22.90 at the  beginning  of the year to $24.11 at the
end of the year).  For a shareholder  who  reinvested the  distributions  in the
purchase of more shares, the total return from the Fund was 14.68% for the year.

As of September  30,  1999,  the Fund had $8.18  billion in net assets.  For the
year, its expense ratio was 0.49% ($4.90 per $1,000 of net assets);  and its net
investment  income  amounted to 3.49% of its  average  net  assets.  It sold and
replaced securities valued at 11% of its net assets.
- --------------------------------------------------------------------------------

"Standard & Poor's(R),"  "S&P(R),"  "S&P  500(R),"  "Standard & Poor's 500," and
"500" are trademarks of The McGraw-Hill Companies, Inc.

<PAGE>

14

INVESTING WITH VANGUARD
The Fund is an investment option in your retirement or savings plan. Your plan
administrator or your employee benefits office can provide you with detailed
information on how to participate in your plan and how to elect the Fund as an
investment option.
o    If you have any questions about the Fund or Vanguard, including those about
     the Fund's investment objective,  strategies,  or risks, contact Vanguard's
     Participant Services Center, toll-free, at 1-800-523-1188.
o    If you have questions about your account,  contact your plan  administrator
     or the organization that provides recordkeeping services for your plan.

INVESTMENT OPTIONS AND ALLOCATIONS
Your  plan's  specific  provisions  may  allow  you to  change  your  investment
selections,  the amount of your  contributions,  or how your  contributions  are
allocated  among the  investment  choices  available  to you.  Contact your plan
administrator or employee benefits office for more details.

TRANSACTIONS
Contributions,  exchanges,  or redemptions of the Fund's shares are processed as
soon as they have been received by Vanguard in good order. Good order means that
your request includes complete  information on your contribution,  exchange,  or
redemption, and that Vanguard has received the appropriate assets.
     In all cases, your transaction will be based on the Fund's  next-determined
net asset value after  Vanguard  receives  your  request (or, in the case of new
contributions,  the  next-determined net asset value after Vanguard receives the
order from your plan administrator).  As long as this request is received before
the close of trading on the New York Stock  Exchange,  generally 4 p.m.  Eastern
time, you will receive that day's net asset value.


EXCHANGES
The exchange  privilege (your ability to redeem shares from one fund to purchase
shares of another  fund) may be available to you through your plan.  Although we
make every  effort to maintain  the exchange  privilege,  Vanguard  reserves the
right to revise or terminate this privilege,  limit the amount of an exchange or
reject any exchange,  at any time, without notice.  Because excessive  exchanges
can potentially  disrupt the management of the Fund and increase its transaction
costs,  Vanguard  limits  participant  exchange  activity  to no more  than FOUR
SUBSTANTIVE  "ROUND TRIPS"  THROUGH THE FUND (at least 90 days apart) during any
12-month  period.  A "round  trip" is a redemption  from the Fund  followed by a
purchase back into the Fund.  "Substantive"  means a dollar amount that Vanguard
determines, in its sole discretion, could adversely affect the management of the
Fund.
     Before  making an exchange to or from another fund  available in your plan,
consider the following:
o    Certain investment options,  particularly funds made up of company stock or
     investment contracts, may be subject to unique restrictions.
o    Make sure to read that fund's  prospectus.  Contact  Participant  Services,
     toll-free, at 1-800-523-1188 for a copy.
o    Vanguard can accept exchanges only as permitted by your plan.  Contact your
     plan  administrator for details on the exchange policies that apply to your
     plan.

<PAGE>

                                                                              15
ACCESSING FUND INFORMATION BY COMPUTER
- --------------------------------------------------------------------------------
VANGUARD ON THE WORLD WIDE WEB www.vanguard.com
Use your personal computer to visit Vanguard's education-oriented website, which
provides  timely news and  information  about  Vanguard  funds and services;  an
online  "university"  that  offers  a  variety  of  mutual  fund  classes;   and
easy-to-use,  interactive  tools to help you  create  your  own  investment  and
retirement strategies.
- --------------------------------------------------------------------------------
<PAGE>

                     (THIS PAGE INTENTIONALLY LEFT BLANK.)

<PAGE>

GLOSSARY OF INVESTMENT TERMS

ACTIVE MANAGEMENT
An investment approach that seeks to exceed the average returns of the financial
markets.  Active  managers  rely on research,  market  forecasts,  and their own
judgment and experience in selecting securities to buy and sell.

BOND
A debt security (IOU) issued by a corporation,  government, or government agency
in exchange for the money you lend it. In most  instances,  the issuer agrees to
pay back the loan by a specific date and to make regular interest payments until
that date.

CAPITAL GAINS DISTRIBUTION
Payment to mutual fund  shareholders  of gains  realized on securities  that the
fund has sold at a profit, minus any realized losses.

CASH RESERVES
Cash deposits,  short-term  bank deposits,  and money market  instruments  which
include U.S.  Treasury bills,  bank  certificates  of deposit (CDs),  repurchase
agreements, commercial paper, and banker's acceptances.

COMMON STOCK
A security  representing  ownership  rights in a  corporation.  A stockholder is
entitled  to share in the  company's  profits,  some of which may be paid out as
dividends.

DIVIDEND INCOME
Payment to  shareholders  of income from  interest or  dividends  generated by a
fund's investments.

EXPENSE RATIO
The  percentage  of a fund's  average net assets used to pay its  expenses.  The
expense ratio  includes  management  fees,  administrative  fees,  and any 12b-1
distribution fees.

FUND DIVERSIFICATION
Holding a variety of securities so that a fund's return is not badly hurt by the
poor performance of a single security, industry, or country.

INDEX
An unmanaged group of securities whose overall performance is used as a standard
to measure investment performance.

INVESTMENT ADVISER
An  organization  that  makes  the  day-to-day   decisions  regarding  a  fund's
investments.

NET ASSET VALUE (NAV)
The market value of a mutual fund's total assets, minus liabilities,  divided by
the  number of shares  outstanding.  The value of a single  share is called  its
share value or share price.

PASSIVE MANAGEMENT
A low-cost  investment strategy in which a mutual fund attempts to match--rather
than  outperform--a  particular  stock  or bond  market  index.  Also  known  as
indexing.

TOTAL RETURN
A percentage change,  over a specified time period, in a mutual fund's net asset
value,  with the ending net asset value adjusted to account for the reinvestment
of all distributions of dividends and capital gains.

VOLATILITY
The  fluctuations  in value of a mutual  fund or other  security.  The greater a
fund's volatility, the wider the fluctuations between its high and low prices.

YIELD
Income  (interest  or  dividends)  earned  by  an  investment,  expressed  as  a
percentage of the investment's price.

<PAGE>

[SHIP LOGO]
[THE VANGUARD GROUP (R) LOGO]
Institutional  Division
Post Office Box 2900
Valley Forge,  PA 19482-2900

FOR MORE INFORMATION
If you'd  like more  information  about  Vanguard  Asset  Allocation  Fund,  the
following documents are available free upon request:

ANNUAL/SEMIANNUAL REPORT TO SHAREHOLDERS
Additional  information about the Fund's  investments is available in the Fund's
annual and semiannual reports to shareholders. In these reports, you will find a
discussion of the market conditions and investment strategies that significantly
affected the Fund's performance during the most recent fiscal year.

STATEMENT  OF  ADDITIONAL  INFORMATION  (SAI)
The SAI provides more detailed information about the Fund.

The  current  annual and  semiannual  reports  and the SAI are  incorporated  by
reference  into (and are thus legally a part of) this  prospectus.

To receive a free copy of the latest annual or semiannual  report or the SAI, or
to request additional information about the Fund or other Vanguard funds, please
contact us as follows:

THE VANGUARD GROUP
PARTICIPANT SERVICES CENTER
P.O. BOX 2900
VALLEY FORGE, PA 19482-2900

TELEPHONE:
1-800-523-1188

TEXT TELEPHONE:
1-800-523-8004

WORLD WIDE WEB:
WWW.VANGUARD.COM

INFORMATION  PROVIDED BY THE  SECURITIES AND EXCHANGE  COMMISSION  (SEC)

You can review and copy  information  about the Fund  (including the SAI) at the
SEC's  Public  Reference  Room in  Washington,  DC. To find out more  about this
public service,  call the SEC at  1-800-SEC-0330.  Reports and other information
about the Fund are also available on the SEC's website (www.sec.gov), or you can
receive copies of this  information,  for a fee, by writing the Public Reference
Section, Securities and Exchange Commission, Washington, DC 20549-6009.


Fund's Investment Company Act
file number: 811-5628

(C) 2000 The Vanguard Group, Inc.
All rights reserved.
Vanguard Marketing Corporation,
Distributor.


I078N-01/21/2000


<PAGE>

                                     PART B

                      VANGUARD(R) ASSET ALLOCATION FUND
                                   (THE FUND)
                      STATEMENT OF ADDITIONAL INFORMATION

                                JANUARY 21, 2000


This Statement is not a prospectus  but should be read in  conjunction  with the
Fund's current Prospectus (dated January 21, 2000). To obtain the Prospectus and
the most recent Annual Report to  Shareholders,  containing the Fund's Financial
Statements, which are hereby incorporated by reference, please call:



                         INVESTOR INFORMATION DEPARTMENT
                             1-800-662-7447 (SHIP)

                               TABLE OF CONTENTS


                                                                            PAGE
                                                                            ----
DESCRIPTION OF THE FUND ...................................................  B-1
INVESTMENT POLICIES .......................................................  B-3
FUNDAMENTAL INVESTMENT LIMITATIONS.........................................  B-8
SHARE PRICE................................................................  B-9
PURCHASE OF SHARES......................................................... B-10
REDEMPTION OF SHARES....................................................... B-10
MANAGEMENT OF THE FUND .................................................... B-10
COMPARATIVE INDEXES ....................................................... B-14
TOTAL RETURN............................................................... B-15
INVESTMENT ADVISORY SERVICES............................................... B-17
PORTFOLIO TRANSACTIONS .................................................... B-19
GLOSSARY................................................................... B-20
FINANCIAL STATEMENTS....................................................... B-21


                            DESCRIPTION OF THE FUND

ORGANIZATION
The Fund was organized as a Maryland corporation in 1988, and was reorganized as
a  Delaware  business  trust  in May,  1998.  Prior to its  reorganization  as a
Delaware  business trust,  the Fund was known as Vanguard Asset Allocation Fund,
Inc.  The Fund is  registered  with the United  States  Securities  and Exchange
Commission (the Commission)  under the Investment  Company Act of 1940 (the 1940
Act) as an open-end, diversified management investment company.

     The Fund has the  ability to offer  additional  funds or classes of shares.
There is no limit on the number of full and fractional shares that the Fund  may
issue for a single fund or class of shares.

SERVICE PROVIDERS
     CUSTODIAN.  State  Street  Bank and Trust  Company,  225  Franklin  Street,
Boston,  Massachusetts  02110, serves as the Fund's custodian.  The custodian is
responsible for maintaining the Fund's assets and keeping all necessary accounts
and records.

INDEPENDENT ACCOUNTANTS.  PricewaterhouseCoopers LLP, 30 South 17th Street,
Philadelphia,  Pennsylvania 19103, serves as the Fund's independent accountants.
The  accountants  audit  financial  statements  for the Fund and  provide  other
related services.
                                      B-1

<PAGE>

     TRANSFER  AND   DIVIDEND-PAYING   AGENT.  The  Fund's  transfer  agent  and
dividend-paying  agent is The Vanguard  Group,  Inc.,  100  Vanguard  Boulevard,
Malvern, Pennsylvania 19355.

CHARACTERISTICS OF THE FUND'S SHARES

     RESTRICTIONS  ON HOLDING OR DISPOSING OF SHARES.  There are no restrictions
on the right of  shareholders  to retain or dispose of the Fund's shares,  other
than the possible future  termination of the Fund. The Fund may be terminated by
reorganization  into another mutual fund or by liquidation  and  distribution of
its assets.  Unless terminated by  reorganization or liquidation,  the Fund will
continue indefinitely.

     SHAREHOLDER  LIABILITY.  The Fund is organized  under  Delaware law,  which
provides  that  shareholders  of a  business  trust  are  entitled  to the  same
limitations of personal  liability as  shareholders  of a corporation  organized
under Delaware law. Effectively,  this means that a shareholder of the Fund will
not be personally liable for payment of the Fund's debts except by reason of his
or her own conduct or acts. In addition,  a shareholder  could incur a financial
loss on account of a Fund  obligation  only if the Fund itself had no  remaining
assets with which to meet such  obligation.  We believe that the  possibility of
such a situation arising is extremely remote.

     DIVIDEND  RIGHTS.  The Fund's  shareholders  are  entitled  to receive  any
dividends or other  distributions  declared by the Fund. No shares have priority
or preference over any other shares with respect to dividends or  distributions.
All dividends and  distributions  will be paid ratably to all Fund  shareholders
according to the number of Fund shares held by shareholders on the record date.

     VOTING  RIGHTS.  Shareholders  are  entitled  to vote on a matter if: (i) a
shareholder  vote is required  under the 1940 Act;  (ii) the matter  concerns an
amendment to the Declaration of Trust that would adversely  affect to a material
degree the rights and  preferences  of the shares of any class or fund; or (iii)
the Trustees determine that it is necessary or desirable to obtain a shareholder
vote.  The 1940 Act requires a  shareholder  vote under  various  circumstances,
including to elect or remove  Trustees upon the written  request of shareholders
representing 10% or more of the Fund's net assets, and to change any fundamental
policy of the Fund.  Fund  shareholders  receive one vote for each dollar of net
asset value owned on the record date, and a fractional  vote for each fractional
dollar  of net  asset  value  owned  on  the  record  date.  Voting  rights  are
non-cumulative and cannot be modified without a majority vote of shareholders.

     LIQUIDATION  RIGHTS.  In the  event of  liquidation,  shareholders  will be
entitled to receive a pro rata share of the Fund's net assets that remain  after
satisfaction of all liabilities.

     PREEMPTIVE  RIGHTS.  There are no  preemptive  rights  associated  with the
Fund's shares.

     CONVERSION  RIGHTS.  There are no  conversion  rights  associated  with the
Fund's shares.

     REDEMPTION  PROVISIONS.  The Fund's redemption  provisions are described in
its  current   prospectus   and  elsewhere  in  this   Statement  of  Additional
Information.

     SINKING FUND PROVISIONS. The Fund has no sinking fund provisions.

     CALLS OR ASSESSMENT. The Fund's shares are fully paid and non-assessable.

TAX STATUS OF THE FUND

The Fund intends to qualify as a "regulated investment company" under Subchapter
M of the Internal Revenue Code. This special tax status means that the Fund will
not be liable  for  federal  tax or income  and  capital  gains  distributed  to
shareholders.  In order to preserve  its tax  status,  the Fund must comply with
certain  requirements.  If the Fund  fails  to meet  these  requirements  in any
taxable  year,  it will be subject  to tax on its  taxable  income at  corporate
rates,  and  all  distributions   from  earnings  and  profits,   including  any
distributions of net tax-exempt income and net  long-termcapital  gains, will be
taxable to  shareholders  as ordinary  income.  In  addition,  the Fund could be
required to recognize unrealized gains, pay substantial taxes and interest,  and
make  substantial  distributions  before regaining its tax status as a regulated
investment company.

                                      B-2

<PAGE>
                              INVESTMENT POLICIES

The following policies supplement the Fund's investment objectives and policies
set forth in the Prospectus:

FUTURES CONTRACTS AND OPTIONS
The Fund may enter into stock index and fixed-income  futures  contracts,  stock
index and fixed income options,  and options on such futures contracts to remain
fully invested as an investment tool when reallocating assets, to add value when
these instruments are favorably prices, to hedge dividend accruals, or to reduce
transactions  costs.  Futures contracts provide for the future sale by one party
and purchase by another  party of a specified  amount of a specific  security or
index at a specified  future time and at a specified  price.  Futures  contracts
which are standardized as to maturity date and underlying  financial  instrument
are traded on national  futures  exchanges.  Futures  exchanges  and trading are
regulated  under the  Commodity  Exchange Act by the Commodity  Futures  Trading
Commission  (CFTC),  a U.S.  Government  Agency.  Assets  committed  to  futures
contracts will be segregated to the extent required by law.

  Although  many  fixed-income  futures  contracts  call for actual  delivery or
acceptance of the underlying securities at a specified date (stock index futures
contracts do not permit  delivery of  securities),  the  contracts  are normally
closed out before the settlement  date without the making or taking of delivery.
Closing out an open  futures  position  is done by taking an  opposite  position
("buying" a contract  which has  previously  been  "sold,"  "selling" a contract
previously  "purchased")  in an identical  contract to terminate  the  position.
Brokerage commissions are incurred when a futures contract is bought or sold.

  Futures  traders are required to make a good faith  margin  deposit in cash or
government  securities  with a broker or custodian to initiate and maintain open
positions  in  futures  contracts.  A  margin  deposit  is  intended  to  assure
completion of the contract  (delivery or acceptance of the underlying  security)
if it is not terminated  prior to the specified  delivery date.  Minimal initial
margin  requirements are established by the futures exchange and may be changed.
Brokers may establish  deposit  requirements  which are higher than the exchange
minimums.  Futures contracts are customarily  purchased and sold on margin which
may range upward from less than 5% of the value of the contract being traded.

  After a futures  contract  position  is opened,  the value of the  contract is
marked to market daily. If the futures contract price changes to the extent that
the  margin  on  deposit  does  not  satisfy  margin  requirements,  payment  of
additional  "variation"  margin  will be  required.  Conversely,  change  in the
contract  value may reduce the  required  margin,  resulting  in a repayment  of
excess margin to the contract holder.  Variation margin payments are made to and
from the  futures  broker for as long as the  contract  remains  open.  The Fund
expects to earn interest income on its margin deposits.

  Traders in futures contracts may be broadly  classified as either "hedgers" or
"speculators."  Hedgers use the futures markets primarily to offset  unfavorable
changes (anticipated or potential) in the value of securities currently owned or
expected  to be  acquired  by them.  Speculators  are less  inclined  to own the
securities  underlying the futures  contracts which they trade,  and use futures
contracts with the  expectation of realizing  profits from  fluctuations  in the
value of the underlying  securities.  The Fund intends to use futures  contracts
for hedging purposes, risk reduction,  securities exposure, liquidity, and other
similar purposes.

  Regulations of the CFTC applicable to the Fund require that all of its futures
transactions constitute bona fide hedging transactions except to the extent that
the aggregate initial margins and premiums required to establish any non-hedging
positions do not exceed five percent of the value of the Fund's portfolio.


                                      B-3

<PAGE>


  RESTRICTIONS  ON THE USE OF FUTURES  CONTRACTS AND OPTIONS.  The Fund will not
enter  into  futures  contract  transactions  to the  extent  that,  immediately
thereafter,  the sum of its initial margin deposits on open contracts exceeds 5%
of the Fund's total  assets;  however,  because  only a small margin  deposit is
required to trade in futures and options,  the Fund may  have up to  50%  of the
value of its assets exposed to futures and options.


  RISK FACTORS IN FUTURES  TRANSACTIONS.  Positions in futures may be closed out
only on an Exchange which provides a secondary market for such futures. However,
there can be no  assurance  that a liquid  secondary  market  will exist for any
particular  futures  contract at any specific time. Thus, it may not be possible
to close a futures position.  In the event of adverse price movements,  the Fund
would  continue  to be required  to make daily cash  payments  to  maintain  its
required margin. In such situations,  if the Fund has insufficient  cash, it may
have to sell portfolio  securities to meet daily margin  requirements  at a time
when it may be  disadvantageous  to do so. The  inability  to close  options and
futures  positions  also could have an  adverse  impact on the  ability to hedge
effectively.

  The Fund will  minimize the risk that it will be unable to close out a futures
contract by only  entering  into  futures  which are traded on national  futures
exchanges and for which there appears to be a liquid secondary market.

  The  risk of loss in  trading  futures  contracts  in some  strategies  can be
substantial, due both to the low margin deposits required, and the potential for
an extremely high degree of leverage involved in futures contracts. As a result,
a relatively  small price movement in a futures contract may result in immediate
and substantial loss (or gain) to the investor.  For example,  if at the time of
purchase,  10% of the value of the futures  contract is deposited  as margin,  a
subsequent  10% decrease in the value of the futures  contract would result in a
total  loss of the margin  deposit,  before any  deduction  for the  transaction
costs,  if the account  were then closed out. A 15%  decrease  would result in a
loss equal to 150% of the original  margin  deposit if the contract  were closed
out.  Thus,  a purchase  or sale of a futures  contract  may result in losses in
excess of the amount posted as initial margin for the contract.  The  Fund  also
bears the risk that  the  Adviser will incorrectly predict future market trends.
However,  because the futures strategies  of  the  Fund  are engaged in only for
hedging purposes,  the adviser does  not believe that the Fund is subject to the
risks of loss frequently associated with futures transactions.  The  Fund  could
presumably have sustained comparable losses if, instead of the futures contract,
it  invests  in  the  underlying  financial  instrument  and  sells it after the
decline.

  Utilization  of  futures  transactions  by the Fund does  involve  the risk of
imperfect or no correlation between the futures price and the value  of securit-
ies underlying futures contracts.  It is  also possible that the Fund could both
lose money on futures  contracts and also  experience a decline  in value of its
portfolio securities.  There is also  the risk of loss by the Fund of margin de-
posits in the event of  bankruptcy  of a  broker with  whom the Fund has an open
position in a futures contract or related option.

  Most  futures  exchanges  limit the amount of  fluctuation  permitted  in some
futures contract prices during a single trading day. The daily limit establishes
the maximum  amount that the price of a futures  contract  may vary either up or
down from the previous day's  settlement  price at the end of a trading session.
Once the daily  limit has been  reached in a  particular  type of  contract,  no
trades may be made on that day at a price  beyond  that  limit.  The daily limit
governs only price movement  during a particular  trading day and therefore does
not limit  potential  losses,  because the limit may prevent the  liquidation of
unfavorable  positions.  Futures contract prices have occasionally  moved to the
daily  limit for  several  consecutive  trading  days with little or no trading,
thereby  preventing  prompt  liquidation of future positions and subjecting some
futures traders to substantial losses.

  FEDERAL TAX TREATMENT OF FUTURES  CONTRACTS.  The Fund is required for Federal
income  tax  purposes  to  recognize  as income  for each  taxable  year its net
unrealized  gains and losses on futures  contracts  as of the end of the year as
well as those actually realized during the year. In most cases, any gain or loss
recognized with respect to a futures contract is considered to be 60%  long-term
capital gain or loss and 40% short-term  capital gain or loss, without regard to
the holding  period of
                                      B-4

<PAGE>

the  contract.  Furthermore,  sales of futures  contracts  which are intended to
hedge  against a change in the value of  securities  held by the Fund may affect
the holding period of such securities and, consequently,  the nature of the gain
or loss on such securities upon  disposition.  The Fund may be required to defer
the recognition of losses on futures contracts to the extent of any unrecognized
gains on related positions held by the Fund.

  In order for the Fund to continue to qualify for Federal  income tax treatment
as a  regulated  investment  company,  at least  90% of its gross  income  for a
taxable year must be derived from qualifying income; i.e.,  dividends,  interest
income derived from loans of  securities,  and gains from the sale of securities
or foreign  currencies,  or other income derived with respect to its business of
investing in such securities or currencies.  It is anticipated that any net gain
realized from the closing out of futures contracts will be considered qualifying
income for purposes of the 90% requirement.

  The Fund will distribute to shareholders  annually any net capital gains which
have been recognized for Federal income tax purposes including  unrealized gains
at the end of the Fund's fiscal year on futures transactions. Such distributions
will be combined  with  distributions  of capital  gains  realized on the Fund's
other  investments  and  shareholders  will  be  advised  on the  nature  of the
payments.

ILLIQUID SECURITIES

The Fund may invest up to 15% of its net assets in illiquid securities. Illiquid
securities  are  securities  that may not be sold or disposed of in the ordinary
course of business  within seven  business  days at  approximately  the value at
which they are being carried on the Fund's books.

  The Fund may invest in restricted, privately placed securities that, under the
Commission's rules,  may be sold only to qualified institutional buyers. Because
these securities can be resold only to qualified  institutional buyers, they may
be  considered  illiquid  securities -- meaning that they could be difficult for
the Fund to convert to cash if needed.

  If a substantial  market develops for a restricted  security held by the Fund,
it will be treated as a liquid  security,  in  accordance  with  procedures  and
guidelines  approved by the Fund's Board of Trustees.  This  generally  includes
securities  that are  unregistered  that can be sold to qualified  institutional
buyers in accordance with Rule 144A under the Securities Act of 1933  (the  1933
Act). While the Fund's investment adviser determines the liquidity of restricted
securities  on  a  daily  basis,   the  Board  oversees  and  retains   ultimate
responsibility for the adviser's decisions.  Several factors the Board considers
in  monitoring  these  decisions  include  the  valuation  of  a  security,  the
availability  of  qualified   institutional  buyers,  and  the  availability  of
information about the security's issuer.

LENDING OF SECURITIES

The Fund may lend its investment securities to qualified institutional investors
(typically brokers,  dealers, banks or other financial institutions) who need to
borrow  securities in order to complete certain  transactions,  such as covering
short sales,  avoiding  failures to deliver  securities or completing  arbitrage
operations. By lending its investment securities,  the Fund attempts to increase
its net investment  income through the receipt of interest on the loan. Any gain
or loss in the market price of the securities loaned that might occur during the
term of the  loan  would be for the  account  of the  Fund.  The  terms  and the
structure  and the aggregate  amount of such loans must be  consistent  with the
1940 Act, and the Rules and  Regulations  or  interpretations  of the Commission
thereunder.  These  provisions limit the amount of securities a fund may lend to
33 1/3% of the Fund's total assets, and require that (a) the borrower pledge and
maintain with the Fund collateral  consisting of cash, an irrevocable  letter of
credit or securities issued or guaranteed by the United States Government having
at all times not less than 100% of the value of the securities  loaned,  (b) the
borrower  add to such  collateral  whenever the price of the  securities  loaned
rises (i.e., the borrower "marks to the market" on a daily basis),  (c) the loan
be made subject to termination by the Fund at any time, and (d) the Fund receive
reasonable interest on the loan (which may include the Fund's investing any cash
collateral in interest bearing short-term investments),  any distribution on the
loaned securities and any increase in their market value. Loan arrangements made
by the Fund

                                      B-5

<PAGE>

will comply with all other  applicable  regulatory  requirements,  including the
rules of the New York Stock  Exchange,  which  presently  require the  borrower,
after notice,  to redeliver the securities  within the normal settlement time of
three  business  days.  All  relevant  facts and  circumstances,  including  the
creditworthiness  of the broker,  dealer or  institution,  will be considered in
making decisions with respect to the lending of securities, subject to review by
the Fund's Board of Trustees.

VANGUARD INTERFUND LENDING PROGRAM

The Commission has issued an exemptive order  permitting the Fund to participate
in Vanguard's interfund lending program.  This program allows the Vanguard funds
to borrow  money from and loan money to each other for  temporary  or  emergency
purposes.  The  program  is  subject to a number of  conditions,  including  the
requirement  that no fund may borrow or lend money through the program unless it
receives a more  favorable  interest rate than is available  from a typical bank
for a comparable transaction. In addition, a fund may participate in the program
only if and to the extent that such  participation is consistent with the fund's
investment  objective and other investment  policies.  The Boards of Trustees of
the Vanguard  funds are  responsible  for ensuring  that the  interfund  lending
program operates in compliance with all conditions of the Commission's exemptive
order.

TEMPORARY INVESTMENTS

The Fund may take temporary  defensive  measures that are inconsistent  with the
Fund's normal fundamental or non-fundamental  investment policies and strategies
in response to adverse market,  economic,  political or other  conditions.  Such
measures could include  investments in (a) highly liquid short-term fixed income
securities issued by or on behalf of municipal or corporate issuers, obligations
of the U.S. Government and its agencies, commercial paper, and bank certificates
of  deposit;  (b) shares of other  investment  companies  which have  investment
objectives  consistent  with  those  of  the  Fund;  (c)  repurchase  agreements
involving any such securities; and (d) other money market instruments.  There is
no limit on the extent to which the Fund may take temporary  defensive measures.
In taking such measures, the Fund may fail to achieve its investment objective.

FOREIGN INVESTMENTS

Vanguard Asset  Allocation Fund may invest up to 20% of its assets in securities
of foreign  companies.  Investors  should  recognize  that  investing in foreign
companies  involves  certain  special  considerations  which  are not  typically
associated with investing in U.S. companies.

  CURRENCY  RISK.   Since  the  stocks  of  foreign   companies  are  frequently
denominated  in  foreign  currencies,  and since the Fund may  temporarily  hold
uninvested  reserves in bank  deposits in foreign  currencies,  the Fund will be
affected  favorably or  unfavorably by changes in currency rates and in exchange
control regulations,  and may incur costs in connection with conversions between
various  currencies.  The investment  policies of Vanguard Asset Allocation Fund
permit it to enter into forward foreign currency exchange  contracts in order to
hedge the Fund's holdings and commitments against changes in the level of future
currency  rates.  Such  contracts  involve an  obligation  to purchase or sell a
specific currency at a future date at a price set at the time of the contract.

  FEDERAL TAX  TREATMENT  OF NON-U.S.  TRANSACTIONS.  Special  rules  govern the
Federal income tax treatment of certain  transactions  denominated in terms of a
currency  other than the U.S.  dollar or determined by reference to the value of
one or more  currencies  other than the U.S.  dollar.  The types of transactions
covered by the special rules include the following:  (i) the  acquisition of, or
becoming the obligor under, a bond or other debt instrument  (including,  to the
extent provided in Treasury regulations,  preferred stock); (ii) the accruing of
certain  trade  receivables  and  payables;  and  (iii)  the  entering  into  or
acquisition  of any  forward  contract,  futures  contract,  option and  similar
financial instrument if such instrument is not marked to market. The disposition
of a currency other than the U.S. dollar by a U.S. taxpayer is also treated as a
transaction subject to the special  currency  rules.  However, foreign currency-
related  regulated futures  contracts and non-equity options are  generally  not
subject to the special  currency  rules if they are or would be  treated as sold
for their fair market

                                      B-6

<PAGE>

value at year-end under the marking-to-market  rules applicable to other futures
contracts  unless an election is made to have such  currency  rules apply.  With
respect to transactions  covered by the special rules,  foreign currency gain or
loss  is  calculated  separately  from  any  gain  or  loss  on  the  underlying
transaction  and is normally  taxable as ordinary  gain or loss.  A taxpayer may
elect to treat as capital  gain or loss  foreign  currency  gain or loss arising
from certain identified  forward  contracts,  futures contracts and options that
are  capital  assets  in the hands of the  taxpayer  and which are not part of a
straddle.  The  Treasury  Department  issued  regulations  under  which  certain
transactions  subject to the special  currency rules that are part of a "section
988 hedging  transaction"  (as defined in the Internal  Revenue Code of 1986, as
amended,  and the  Treasury  regulations)  will be  integrated  and treated as a
single  transaction or otherwise treated  consistently for purposes of the Code.
Any gain or loss attributable to the foreign currency component of a transaction
engaged in by a Fund which is not subject to the special currency rules (such as
foreign equity  investments other than certain preferred stocks) will be treated
as capital gain or loss and will not be segregated  from the gain or loss on the
underlying   transaction.   It  is   anticipated   that  some  of  the  non-U.S.
dollar-denominated  investments and foreign  currency  contracts  Vanguard Asset
Allocation  Fund may make or enter into will be subject to the special  currency
rules described above.

  COUNTRY  RISK.  As  foreign  companies  are not  generally  subject to uniform
accounting,  auditing and financial reporting standards and practices comparable
to those applicable to domestic companies,  there may be less publicly available
information  about certain  foreign  companies  than about  domestic  companies.
Securities of some foreign companies are generally less liquid and more volatile
than  securities  of  comparable  domestic  companies.  There is generally  less
government  supervision  and regulation of stock  exchanges,  brokers and listed
companies  than in the  U.S.  In  addition,  with  respect  to  certain  foreign
countries,  there is the possibility of expropriation or confiscatory  taxation,
political or social instability,  or diplomatic  developments which could affect
U.S. investments in those countries.

  Although the Fund will endeavor to achieve most favorable  execution  costs in
their portfolio transactions,  fixed commissions on many foreign stock exchanges
are generally higher than negotiated commissions on U.S. exchanges. In addition,
it is  expected  that the  expenses  for  custodian  arrangements  of the Fund's
foreign  securities will be somewhat greater than the expenses for the custodian
arrangements for handling U.S. securities of equal value.

  Certain  foreign  governments  levy  withholding  taxes  against  dividend and
interest  income.  Although  in some  countries  a  portion  of  these  taxes is
recoverable,  the non-recovered portion of foreign withholding taxes will reduce
the income received from foreign companies held by the Fund.

DESCRIPTION OF U.S. GOVERNMENT SECURITIES

As used in this Statement of Additional  Information,  the term "U.S. Government
Securities"  refers to a variety of securities which are issued or guaranteed by
the United States Treasury, by various agencies of the United States Government,
and by various instrumentalities which have been established or sponsored by the
United  States  Government.  The term  also  refers to  "repurchase  agreements"
collateralized by such securities.

  U.S.  Treasury  Securities  are backed by the "full  faith and  credit" of the
United  States.  Securities  issued or guaranteed  by Federal  agencies and U.S.
Government  sponsored  instrumentalities  may or may not be  backed  by the full
faith and credit of the United  States.  In the case of securities not backed by
the full  faith  and  credit  of the  United  States,  the  investor  must  look
principally  to the  agency  or  instrumentality  issuing  or  guaranteeing  the
obligation for ultimate repayment, and may not be able to assert a claim against
the United  States  itself in the event the agency or  instrumentality  does not
meet its commitment.

  Some of the  U.S.  Government  agencies  that  issue or  guarantee  securities
include   the   Export-Import   Bank  of  the  United   States,   Farmers   Home
Administration,  Federal Housing Administration,  Maritime Administration, Small
Business Administration, and The Tennessee Valley Authority.


                                      B-7

<PAGE>

  An  instrumentality  of the U.S.  Government is a government  agency organized
under Federal charter with government supervision.  Instrumentalities issuing or
guaranteeing  securities  include,  among others,  Federal Home Loan Banks,  the
Federal Land Banks,  Central Bank for Cooperatives,  Federal Intermediate Credit
Banks, and the Federal National Mortgage Association.

DESCRIPTION OF REPURCHASE AGREEMENTS

Repurchase  agreements are  transactions by which a person  purchases a security
and simultaneously  commits to resell that security to the seller (a member bank
of the Federal Reserve System or recognized securities dealer) at an agreed upon
price on an agreed  upon date  within a number  of days  (usually  not more than
seven) from the date of purchase.  The resale price  reflects the purchase price
plus an agreed upon market rate of  interest  which is  unrelated  to the coupon
rate or maturity of the purchased security.  A repurchase agreement involves the
obligation  of the seller to pay the agreed upon price,  which  obligation is in
effect secured by the value of the underlying security.

  The use of repurchase  agreements  involves certain risks. For example, if the
seller of the agreement  defaults on its obligation to repurchase the underlying
securities at a time when the value of these securities has declined,  the  Fund
may incur a loss  upon  disposition  of them.  If the  seller  of the  agreement
becomes  insolvent  and  subject  to  liquidation  or  reorganization  under the
Bankruptcy  Code or other  laws,  a  bankruptcy  court  may  determine  that the
underlying  securities  are  collateral  not  within the control of the Fund and
therefore subject to sale by the trustee in bankruptcy.  Finally, it is possible
that the Fund may  not be able to substantiate its  interest  in the  underlying
securities. While the Fund's management acknowledges these risks, it is expected
that they can be controlled  through stringent  security  selection criteria and
careful monitoring procedures.

                       FUNDAMENTAL INVESTMENT LIMITATIONS

The Fund is subject to the following fundamental investment  limitations,  which
cannot be changed in any  material  way without the approval of the holders of a
majority of the Fund's shares.  For these  purposes,  a "majority" of the Fund's
shares  means  shares  representing  the lesser of: (i) 67% or more of the votes
cast to approve a change,  so long as shares  representing  more than 50% of the
Fund's net asset value are present or  represented  by proxy;  or (ii) more than
50% of the Fund's net asset value.

  BORROWING.  The Fund may not borrow  money,  except for temporary or emergency
purposes in an amount not exceeding  15% of the Fund's net assets.  The Fund may
borrow  money  through  banks,  reverse  repurchase  agreements,  or  Vanguard's
interfund  lending program only, and must comply with all applicable  regulatory
conditions.  The  Fund  may not make any  additional  investments  whenever  its
outstanding borrowings exceed 5% of net assets.

  COMMODITIES. The Fund may not invest in commodities, except that it may invest
in bond or stock  index futures contracts,  bond or stock options and options on
bond or stock index  futures  contracts.  No  more  than  5% of the Fund's total
assets may be used as initial margin deposit for futures contracts,  and no more
than 50% of the Fund's  total  assets may be  invested in futures  contracts  or
options at any time.

  DIVERSIFICATION.  With respect to 75% of its total  assets,  the Fund may not:
(i)  purchase  more than 10% of the  outstanding  voting  securities  of any one
issuer; or (ii) purchase  securities of any issuer if, as a result, more than 5%
of the Fund's total assets would be invested in that issuer's  securities.  This
limitation  does not apply to obligations of the United States  Government,  its
agencies, or instrumentalities.

  INDUSTRY CONCENTRATION.  The  Fund  may  not invest more than 25% of its total
assets in any one industry.

  INVESTING FOR CONTROL.  The  Fund  may not invest in a company for purposes of
controlling its management.

                                      B-8
<PAGE>

  INVESTMENT COMPANIES. The Fund may not invest in any other investment company,
except  through a merger,  consolidation  or  acquisition  of assets,  or to the
extent  permitted  by Section  12 of the 1940 Act.  Investment  companies  whose
shares the Fund acquires pursuant to Section 12 must have investment  objectives
and investment policies consistent with those of the Fund.

  LOANS.  The Fund may not lend money to any person except by  purchasing  fixed
income  securities  that  are  publicly   distributed,   lending  its  portfolio
securities, or through Vanguard's interfund lending program.

  MARGIN.  The  Fund may  not  purchase  securities on margin or sell securities
short, except as permitted by the Fund's  investment  policies  relating to com-
modities.

  PLEDGING ASSETS.  The  Fund  may not pledge, mortgage or hypothecate more than
15% of its net assets.

  REAL ESTATE. The Fund may not invest directly in real estate,  although it may
invest in securities of companies  that deal in real estate and bonds secured by
real estate.

  SENIOR SECURITIES. The Fund may not issue senior securities, except in compli-
ance with the 1940 Act.

  UNDERWRITING.  The Fund may not engage in the business of underwriting securi-
ties issued by other persons.The Fund will not be considered an underwriter when
disposing of its investment securities.

  The investment  limitations  above are considered at the time that  investment
securities are purchased.

  None of these limitations prevents the Fund from participating in The Vanguard
Group  (Vanguard).  Because the Fund is a member of the Group,  the Fund may own
securities  issued by  Vanguard,  make  loans  to  Vanguard,  and  contribute to
Vanguard's costs or other financial requirement.  See  "Management of  the Fund"
for more information.

                                  SHARE PRICE

The Fund's  share  price,  or "net asset  value" per  share,  is  calculated  by
dividing the total assets of the Fund, less all liabilities, by the total number
of shares outstanding.  The net asset value is determined as of the close of the
New York Stock Exchange  (generally 4:00 p.m. Eastern time) on each day that the
Exchange is open for trading.

  Portfolio  securities  for  which  market  quotations  are  readily  available
(includes those securities listed on national securities  exchanges,  as well as
those quoted on the NASDAQ Stock Market) will be valued at the last quoted sales
price on the day the valuation is made. Such securities  which are not traded on
the  valuation  date are  valued  at the mean of the bid and ask  prices.  Price
information on  exchange-listed  securities is taken from the exchange where the
security is primarily  traded.  Any foreign  securities are valued at the latest
quoted sales price available before the time when assets are valued.  Securities
may be valued on the basis of prices  provided  by a pricing  service  when such
prices are believed to reflect the fair market value of such securities.

  Short-term instruments (those acquired with remaining maturities of 60 days or
less) may be valued at cost,  plus or minus any  amortized  discount or premium,
which approximates market value.

  Bonds and other fixed income  securities  may be valued on the basis of prices
provided by a pricing  service when such prices are believed to reflect the fair
market value of such securities. The prices provided by a pricing service may be
determined without regard to bid or last sale prices of each security,  but take
into account institutional-size  transactions in similar groups of securities as
well as any developments related to specific securities.

  Other assets and securities  for which no quotations are readily  available or
which are  restricted  as to sale (or resale) are valued by such  methods as the
Board of Trustees deems in good faith to reflect fair value.

                                      B-9

<PAGE>
  The share price for the Fund can be found daily in the mutual fund listings of
most major newspapers under the heading of "Vanguard Funds."

                           PURCHASE OF SHARES

The Fund reserves the right in its sole discretion  (i) to suspend the offerings
of its shares, (ii) to reject purchase orders when in the judgment of management
such rejection is in the best interest of the Fund, and (iii) to reduce or waive
the minimum  investment for or any other  restrictions on initial and subsequent
investments for certain fiduciary accounts or under  circumstances where certain
economies can be achieved in sales of the Fund's shares.

                              REDEMPTION OF SHARES

The Fund may suspend  redemption  privileges or postpone the date of payment (i)
during any period that the New York Stock Exchange is closed,  or trading on the
Exchange is restricted as determined by the  Commission,  (ii) during any period
when an emergency  exists as defined by the rules of the  Commission as a result
of which it is not reasonably  practicable for the Fund to dispose of securities
owned by it, or fairly to determine the value of its assets,  and (iii) for such
other periods as the  Commission  may permit.  No charge is made by the Fund for
redemptions.  Shares  redeemed  may be worth more or less than what was paid for
them, depending on the market value of the securities held by the Fund.

     The Fund  has  made an  election  with  the  Commission  to pay in cash all
redemption  requested by any  shareholder of record limited in amount during any
90-day  period to the lesser of  $250,000 or 1% of the net assets of the Fund at
the beginning of such period.


TRADING SHARES THROUGH CHARLES SCHWAB

The Fund has  authorized  Charles  Schwab & Co., Inc.  (Schwab) to accept on its
behalf purchase and redemption orders under certain terms and conditions. Schwab
is also  authorized to designate  other  intermediaries  to accept  purchase and
redemption  orders on the Fund's behalf  subject to those terms and  conditions.
Under this  arrangement,  the Fund will be deemed to have received a purchase or
redemption order when Schwab or, if applicable,  Schwab's  authorized  designee,
accepts the order in accordance  with the Fund's  instructions.  Customer orders
that are properly transmitted to the Fund by Schwab, or if applicable,  Schwab's
authorized designee, will be priced as follows:

  Orders received by Schwab before 3 p.m. Eastern time on any business day, will
be sent to Vanguard  that day and  your share price will be based on the  Fund's
net asset value  calculated at the close of trading that day. Orders received by
Schwab  after 3 p.m.  Eastern  time,  will be sent to Vanguard on the  following
business  day and your  share  price will be based on the Fund's net asset value
calculated at the close of trading that day.

                             MANAGEMENT OF THE FUND

TRUSTEES AND OFFICERS

The officers of the Fund manage its day-to-day operations and are responsible to
the Fund's Board of Trustees.  The Trustees set broad  policies for the Fund and
choose its  officers.  The  following  is a list of Trustees and officers of the
Fund and a statement of their present positions and principal occupations during
the past five years. As a group,  the Fund's Trustees and officers own less than
1% of the outstanding shares of the Fund. Each Trustee also serves as a Director
of   The  Vanguard  Group,   Inc.,  and  as a  Trustee  of each of the 103 funds
administered by Vanguard (102 in the case of Mr. Malkiel and 93  in the case  of
Mr.  MacLaury).  The mailing address of the Trustees and officers of the Fund is
Post Office Box 876, Valley Forge, PA 19482.

                                      B-10
<PAGE>

JOHN J. BRENNAN,  (DOB: 7/29/1954) Chairman,  Chief Executive Officer & Trustee*
Chairman,  Chief Executive Officer and Director of The Vanguard Group, Inc., and
Trustee of each of the investment companies in The Vanguard Group.

JOANN  HEFFERNAN  HEISEN,  (DOB:   1/25/1950)  Trustee
Vice President, Chief Information Officer, and member of the Executive Committee
of Johnson & Johnson (Pharmaceuticals/Consumer  Products), Director of Johnson &
Johnson*MERCK Consumer Pharmaceuticals Co., The Medical Center at Princeton, and
Women's Research and Education Institute.

BRUCE K. MACLAURY,  (DOB:  5/7/1931) Trustee
President  Emeritus  of  The  Brookings  Institution  (Independent  Non-Partisan
Research  Organization);  Director of American  Express Bank Ltd.,  The St. Paul
Companies, Inc. (Insurance and Financial Services), and National Steel Corp.

BURTON G. MALKIEL,  (DOB:  8/28/1932) Trustee
Chemical Bank Chairman's Professor of Economics, Princeton University;  Director
of Prudential Insurance Co. of America, Banco Bilbao Gestinova, Baker Fentress &
Co.  (Investment  Management),  The Jeffrey Co.  (Holding  Company),  and Select
Sector SPDR Trust (Exchange-Traded Mutual Fund).

ALFRED M. RANKIN,  JR., (DOB:  10/8/1941)  Trustee
Chairman,  President, Chief Executive Officer, and Director of NACCO Industries,
Inc. (Machinery/ Coal/Appliances);  and Director of The BFGoodrich Co. (Aircraft
Systems/Manufacturing/Chemicals).

JOHN C. SAWHILL, (DOB: 6/12/1936) Trustee
President  and Chief  Executive  Officer of The Nature  Conservancy  (Non-Profit
Conservation Group);  Director of Pacific Gas and Electric Co., Procter & Gamble
Co., NACCO Industries  (Machinery/ Coal/ Appliances),  and Newfield  Exploration
Co.  (Energy);   formerly,  Director  and  Senior  Partner  of  McKinsey  &  Co.
(Consultants), and President of New York University.

JAMES O. WELCH, JR., (DOB: 5/13/1931) Trustee
Retired Chairman of Nabisco Brands, Inc. (Food Products);  retired Vice Chairman
and  Director  of RJR  Nabisco  (Food and  Tobacco  Products);  Director of TECO
Energy, Inc., and Kmart Corp.

J. LAWRENCE WILSON, (DOB: 3/2/1936) Trustee
Retired Chairman of Rohm & Haas Co. (Chemicals);  Director of Cummins Engine Co.
(Diesel Engine Company),  and The Mead Corp.  (Paper  Products);  and Trustee of
Vanderbilt University.

RAYMOND J. KLAPINSKY, (DOB: 12/7/1938) Secretary*
Managing Director of The Vanguard Group, Inc.;  Secretary of The Vanguard Group,
Inc. and of each of the investment companies in The Vanguard Group.

THOMAS J. HIGGINS, (DOB: 5/21/1957) Treasurer*
Principal  of The Vanguard  Group,  Inc.;  Treasurer  of each of the  investment
companies in The Vanguard Group.

ROBERT D. SNOWDEN, (DOB: 9/4/1961) Controller*
Principal of The Vanguard  Group,  Inc.;  Controller  of each of the  investment
companies in The Vanguard Group

* Officers of the Fund are "interested persons" as defined in the 1940 Act.


     The Fund is a member of The Vanguard Group of Investment  Companies,  which
consists  of more than 35  investment  companies.  Through  their  jointly-owned
subsidiary, The Vanguard Group, Inc. (Vanguard), the Fund and the other funds in
Vanguard   obtain  at  cost  virtually  all  of  their   corporate   management,
administrative  and  distribution  services.  Vanguard also provides  investment
advisory services on an at-cost basis to certain of the Vanguard funds.
     Vanguard  employs  a  supporting  staff of  management  and  administrative
personnel  needed  to  provide  the  requisite  services  to the  funds and also
furnishes the funds with necessary office space, furnishings and equipment. Each
fund pays its share of Vanguard's  total expenses which are

                                      B-11
<PAGE>

allocated  among the funds  under  methods  approved by the Board of Trustees of
each fund. In addition,  each fund bears its own direct  expenses such as legal,
auditing,  and  custodian  fees.

     The Fund's officers are also officers and employees of Vanguard. No officer
or employee owns, or is permitted to own, any securities of any external adviser
for the funds.

     Vanguard  adheres to a Code of Ethics  established  pursuant  to Rule 17j-1
under the 1940 Act.  The Code is  designed  to  prevent  unlawful  practices  in
connection  with the purchase or sale of securities by persons  associated  with
Vanguard.  Under  Vanguard's  Code of Ethics  certain  officers and employees of
Vanguard who are  considered  access persons are permitted to engage in personal
securities  transactions.  However,  such transactions are subject to procedures
and  guidelines  similar  to,  and in many cases more  restrictive  than,  those
recommended by a blue ribbon panel of mutual fund industry executives.

     Vanguard was  established and operates under an Amended and Restated Funds'
Service  Agreement which was approved by the  shareholders of each of the funds.
The amounts which each of the funds have invested are adjusted from time to time
in order to maintain the proportionate relationship between each Fund's relative
net assets and its contribution to Vanguard's capital.  The Amended and Restated
Funds'  Service  Agreement  provides  that: (a) each Vanguard fund may be called
upon to invest up to 0.40% of its current assets in Vanguard, and (b)there is no
limit on the dollar amount that each Vanguard fund may  contribute to Vanguard's
capitalization.  At September  30,  1999,  the Fund had  contributed  capital of
$1,770,000, representing 1.8% of Vanguard's capitalization.

MANAGEMENT
Corporate  management and administrative  services include: (1) executive staff;
(2) accounting and financial; (3) legal and regulatory;  (4) shareholder account
maintenance;  (5)  monitoring  and  control  of  custodian  relationships;   (6)
shareholder  reporting;  and (7) review and  evaluation  of  advisory  and other
services provided to the funds by third parties.

DISTRIBUTION
Vanguard Marketing Corporation, a wholly-owned subsidiary of The Vanguard Group,
Inc.  provides all  distribution  and marketing  activities for the funds in the
Group.  The principal  distribution  expenses are for  advertising,  promotional
materials  and  marketing  personnel.  Distribution  services  may also  include
organizing  and  offering  to the  public,  from  time to time,  one or more new
investment  companies  which will  become  members of The  Vanguard  Group.  The
Trustees and officers of Vanguard  determine the amount to be spent  annually on
distribution  activities,  the manner  and amount to be spent on each fund,  and
whether to organize  new  investment  companies.  One-half  of the  distribution
expenses of a marketing  and  promotional  nature is  allocated  among the funds
based upon  relative net assets.  The  remaining  one-half of those  expenses is
allocated  among the funds based upon each  fund's  sales for the  preceding  24
months relative to the total sales of the funds as a Group,  provided,  however,
that no  fund's  aggregate  quarterly  rate  of  contribution  for  distribution
expenses of a marketing  and  promotional  nature  shall  exceed 125% of average
distribution  expense rate for The Vanguard Group,  and that no fund shall incur
annual distribution  expenses in excess of 20/100 of 1% of its average month-end
net assets.

     During the fiscal years ended September 30, 1997,  1998, and 1999, the Fund
incurred the following  approximate  amounts of The Vanguard Group's  management
(including  transfer agency), distribution, and marketing expenses: $11,315,000,
$18,555,000, and $29,870,000, respectively.


INVESTMENT ADVISORY SERVICES

Vanguard provides investment advisory services to several Vanguard funds.  These
services are provided on an at-cost basis from a money management staff employed
directly by Vanguard. The compensation and other expenses of this staff are paid
by the funds utilizing these services.

                                      B-12
<PAGE>

TRUSTEE COMPENSATION

The  same  individuals  serve  as  Trustees  of all  Vanguard  funds  (with  two
exceptions,  which  are  noted  in  the  table  below),  and  each  fund  pays a
proportionate  share of the  Trustees'  compensation.  The  funds  employ  their
officers on a shared basis,  as well.  However,  officers are compensated by The
Vanguard Group, Inc., not the funds.

  INDEPENDENT TRUSTEES. The funds compensate their independent Trustees -- that
is, the ones who are not also officers of the Fund in three ways:

o The independent Trustees receive an annual fee for their service to the funds,
  which is subject to reduction based on absences from scheduled Board meetings.


o The independent Trustees are reimbursed for the travel and other expenses that
  they incur in attending Board meetings.

o Upon retirement,  the independent  Trustees receive an aggregate annual fee of
  $1,000 for each year served on the Board, up to fifteen years of service. This
  annual fee is paid for ten years following retirement, or until each Trustee's
  death.


     "INTERESTED"  TRUSTEES.  The funds'  interested  Trustee -- Mr.  Brennan --
receives no compensation for his service in that capacity.  However,  he is paid
in his role as officer of The Vanguard Group, Inc.

     COMPENSATION TABLE. The following table provides  compensation  details for
each of the Trustees.  We list the amounts paid as  compensation  and accrued as
retirement benefits by the Fund for each Trustee.  In addition,  the table shows
the total  amount of benefits  that we expect each  Trustee to receive  from all
Vanguard funds upon  retirement,  and the total amount of  compensation  paid to
each Trustee by all Vanguard funds. All information shown is for the fiscal year
ended September 30, 1999.


               VANGUARD ASSET ALLOCATION FUND COMPENSATION TABLE



                                        PENSION OR                     TOTAL
                                        RETIREMENT                  COMPENSATION
                                         BENEFITS     ESTIMATED       FROM ALL
                         AGGREGATE      ACCRUED AS      ANNUAL        VANGUARD
                        COMPENSATION  PART OF THIS  BENEFITS UPON  FUNDS PAID TO
  NAMES OF TRUSTEES   FROM THIS FUND  FUND'S EXPENSES  RETIREMENT    TRUSTEES(1)
- --------------------------------------------------------------------------------
John C. Bogle(2) . . .  .   None          None            None           None
John J. Brennan. . . .  .   None          None            None           None
JoAnn Heffernan Heisen  .  1,400           $77         $15,000        $80,000
Bruce K. MacLaury. . . .  $1,453          $131         $12,000        $75,000
Burton G. Malkiel. . . .. $1,411          $128         $15,000        $80,000
Alfred M. Rankin, Jr.. .. $1,400           $93         $15,000        $80,000
John C. Sawhill. . . . .. $1,400          $118         $15,000        $80,000
James O. Welch, Jr.. . .. $1,400          $137         $15,000        $80,000
J. Lawrence Wilson . . .. $1,400           $99         $15,000        $80,000

(1) The amounts reported in this column reflect the total  compensation  paid to
    each  Trustee for their  service as Trustee of 103 funds(103 in the case of
    Mr. Malkiel; 93 in the case of Mr. MacLaury).
(2) Mr. Bogle retired from the Trust's Board, effective December 31, 1999.


                                      B-13
<PAGE>

                              COMPARATIVE INDEXES

Vanguard may use reprinted  material  discussing The Vanguard Group, Inc. or any
of the member funds of The Vanguard Group of Investment  Companies.  Each of the
investment  company  members of The Vanguard  Group,  including  Vanguard  Asset
Allocation  Fund,  may,  from  time to  time,  use one or more of the  following
unmanaged indexes for comparative performance purposes.

STANDARD & POOR'S 500 COMPOSITE STOCK PRICE INDEX -- included stocks selected by
Standard & Poor's  Index  Committee  to  include  leading  companies  in leading
industries and to reflect the U.S. stock market.

STANDARD & POOR'S  MIDCAP 400 INDEX -- is composed of 400 medium sized  domestic
stocks.

STANDARD & POOR'S  SMALLCAP  600/BARRA VALUE INDEX -- contains stocks of the S&P
SmallCap 600 Index which have a lower than average price-to-book ratio.

STANDARD & POOR'S SMALLCAP  600/BARRA GROWTH INDEX -- contains stocks of the S&P
SmallCap 600 Index which have a higher than average price-to-book ratio.

RUSSELL  1000 VALUE INDEX --  consists  of the stocks in the Russell  1000 Index
(comprising  the 1,000  largest  U.S.-based  companies  measured by total market
capitalization)  with the lowest  price-to-book  ratios,  comprising  50% of the
market capitalization of the Russell 1000.

WILSHIRE 5000 EQUITY INDEX -- consists of nearly 7,000 common equity securities,
covering all stocks in the U.S. for which daily pricing is available.

WILSHIRE 4500 EQUITY INDEX -- consists of all stocks in the Wilshire 5000 except
for the 500 stocks in the Standard and Poor's 500 Index.

MORGAN STANLEY  CAPITAL  INTERNATIONAL  EAFE INDEX -- is an  arithmetic,  market
value-weighted  average of the performance of over 900 securities  listed on the
stock exchanges of countries in Europe, Australia, Asia and the Far East.

GOLDMAN SACHS 100 CONVERTIBLE  BOND INDEX -- currently  includes 71 bonds and 29
preferreds.   The  original  list  of  names  was  generated  by  screening  for
convertible  issues of $100  million or greater  in market  capitalization.  The
index is priced monthly.

SALOMON BROTHERS GNMA INDEX -- includes pools of mortgages originated by private
lenders and guaranteed by the mortgage pools of the Government National Mortgage
Association.

SALOMON BROTHERS HIGH-GRADE CORPORATE BOND INDEX -- consists of publicly issued,
non-convertible  corporate bonds rated AA or AAA. It is a value-weighted,  total
return index, including  approximately 800 issues with maturities of 12 years or
greater.

LEHMAN BROTHERS AGGREGATE BOND INDEX -- is a market weighted index that contains
over 4,000 individually priced U.S. Treasury,  agency,  corporate,  and mortgage
pass-through  securities corporate rated BBB - or better. The Index has a market
value of over $5 trillion.

LEHMAN  BROTHERS  MUTUAL  FUND SHORT  (1-5)  GOVERNMENT/CORPORATE  INDEX -- is a
market  weighted  index  that  contains  over  1,500  individually  priced  U.S.
Treasury,  agency,  and corporate  investment  grade bonds rated BBB - or better
with maturities between one and five years. The index has a market value of over
$1.6 trillion.

LEHMAN BROTHERS MUTUAL FUND INTERMEDIATE (5-10) GOVERNMENT/CORPORATE INDEX -- is
a market  weighted  index that  contains  over 1,500  individually  priced  U.S.
Treasury, agency, and corporate securities rated BBB - or better with maturities
between five and ten years. The index has a market value of over $800 billion.

LEHMAN  BROTHERS LONG (10+)  GOVERNMENT/CORPORATE  INDEX -- is a market weighted
index that contains over 1,900 individually  priced U.S.  Treasury,  agency, and
corporate  securities  rated BBB - or better  with  maturities greater  than ten
years. The index has a market value of over $1.1 trillion.

                                      B-14
<PAGE>

LEHMAN LONG-TERM TREASURY BOND INDEX -- is a market weighted index that contains
individually  priced U.S.  Treasury  securities  with maturities of ten years or
greater.

MERRILL LYNCH  CORPORATE & GOVERNMENT  BOND INDEX -- consists of over 4,500 U.S.
Treasury, Agency and investment grade corporate bonds.

LEHMAN   CORPORATE  (BAA)  BOND  INDEX  --  all  publicly  offered  fixed  rate,
nonconvertible  domestic  corporate bonds rated Baa by Moody's,  with a maturity
longer  than one year and with more than $100  million  outstanding.  This index
includes over 1,500 issues.

LEHMAN  BROTHERS  LONG-TERM  CORPORATE  BOND  INDEX -- is a subset of the Lehman
Corporate  Bond Index  covering  all  corporate,  publicly  issued,  fixed-rate,
nonconvertible  U.S.  debt issues rated at least Baa, with at least $100 million
principal outstanding and maturity greater than ten years.

BOND BUYER MUNICIPAL BOND INDEX -- is a yield index on current coupon high grade
general obligation municipal bonds.

STANDARD & POOR'S  PREFERRED  INDEX -- is a yield  index  based upon the average
yield of four high grade, noncallable preferred stock issues.

NASDAQ INDUSTRIAL INDEX -- is composed of more than 3,000 industrial  issues. It
is a  value-weighted  index calculated on price change only and does not include
income.

COMPOSITE  INDEX -- 70%  Standard & Poor's  500 Index and 30% NASDAQ  Industrial
Index.

COMPOSITE  INDEX -- 65%  Standard & Poor's  500 Index and 35%  Lehman  Long-Term
Corporate AA or Better Bond Index.

COMPOSITE INDEX -- 65% Lehman Long-Term  Corporate AA or Better Bond Index and a
35% weighting in a blended equity  composite (75% Standard & Poor's/BARRA  Value
Index,  12.5%  Standard  & Poor's  Utilities  Index and 12.5%  Standard & Poor's
Telephone Index).

LEHMAN  LONG-TERM  CORPORATE AA OR BETTER BOND INDEX -- consists of all publicly
issued,  fixed  rate,  nonconvertible   investment  grade,   dollar-denominated,
SEC-registered corporate debt rated AA or AAA.

                                  TOTAL RETURN

The average  annual  total return for the Fund for the one,  five,  and ten year
periods ended September 30, 1999 was +14.68%, +20.45% and +14.60%, respectively.

AVERAGE ANNUAL TOTAL RETURN

Average annual total return is the average annual  compounded rate of return for
the  periods of one year,  five  years,  ten years or the life of the Fund,  all
ended on the last day of a recent month.  Average annual total return quotations
will  reflect  changes  in the price of the Fund's  shares  and assume  that all
dividends and capital gains  distributions  during the  respective  periods were
reinvested in Fund shares.  Average annual total return is calculated by finding
the average annual compounded rates of return of a hypothetical  investment over
such periods  according to the following formula (average annual total return is
then expressed as a percentage):

                               T = (ERV/P)1/N-1
  Where:

          T    = average annual total return
          P    = a hypothetical  initial investment of $1,000
          n    = number of years
          ERV  = ending  redeemable  value:  ERV is the value,
                 at the end of the applicable period, of a
                 hypothetical $1,000 investment made at the
                 beginning of the applicable period.


                                      B-15
<PAGE>


AVERAGE ANNUAL AFTER-TAX TOTAL RETURN QUOTATION
We calculate the Fund's  average  annual  after-tax  total return by finding the
average  annual  compounded  rate of return over the one-,  five-,  and ten-year
periods (or for periods of the Fund's  operations) that would equate the initial
amount invested to the after-tax value, according to the following formulas:

AFTER-TAX RETURN:
                                 P (1+T)N = ATV
     Where:
              P   = a hypothetical  initial payment of $1,000
              T   = average annual after-tax total return
              n   = number of years
            ATV   = after-tax value at the end of the one-,  five-, or
                    ten-year  periods of a hypothetical  $1,000 payment
                    made at the beginning of the time period,  assuming
                    no  liquidation of the investment at the end of the
                    measurement periods.

INSTRUCTIONS.

1.   Assume all distributions by the Fund are  reinvested--less the taxes due on
     such  distributions--  at the price on the  reinvestment  dates  during the
     period.  Adjustments  may be made for  subsequent  re-characterizations  of
     distributions.

2.   Calculate  the  taxes  due on  distributions  by the Fund by  applying  the
     highest federal  marginal tax rates to each component of the  distributions
     on the reinvestment date (e.g.,  ordinary income,  short-term capital gain,
     long-term  capital gain,  etc.).  For periods after  December 31, 1997, the
     federal marginal tax rates used for the calculations are 39.6% for ordinary
     income and  short-term  capital gains and 20% for long-term  capital gains.
     Note that the  applicable tax rates may vary over the  measurement  period.
     Assume no taxes are due on the portions of any distributions  classified as
     exempt  interest  or  non-taxable  (i.e.,  return of  capital).  Ignore any
     potential tax liabilities other than federal tax liabilities  (e.g.,  state
     and local taxes).

3.   Include al recurring fees that are charged to all shareholder accounts. For
     any account fees that vary with the size of the account,  assume an account
     size equal to the Fund's  mean (or  median)  account  size.  Assume that no
     additional  taxes or tax  credits  result  from any  redemption  of  shares
     required to pay such fees.

4.   State the total return quotation to the nearest hundredth of one percent.



CUMULATIVE TOTAL RETURN

Cumulative  total  return is the  cumulative  rate of  return on a  hypothetical
initial  investment of $1,000 for a specified  period.  Cumulative  total return
quotations reflect changes in the price of the Fund's shares and assume that all
dividends and capital gains  distributions  during the period were reinvested in
Fund shares.  Cumulative  total return is calculated  by finding the  cumulative
rates of a return of a hypothetical  investment over such periods,  according to
the  following  formula   (cumulative  total  return  is  then  expressed  as  a
percentage):

                                 C = (ERV/P)-1
  Where:

          C    = cumulative total return
          P    = a  hypothetical  initial  investment  of  $1,000
          ERV  = ending redeemable value: ERV is the value, at the end
                 of the applicable period, of a hypothetical $1,000
                 investment made at the beginning of the applicable period.

                                      B-16
<PAGE>

SEC YIELDS

Yield is the net  annualized  yield based on a  specified  30-day (or one month)
period  assuming  semiannual  compounding  of  income.  Yield is  calculated  by
dividing the net  investment  income per share  earned  during the period by the
maximum offering price per share on the last day of the period, according to the
following formula:

                          YIELD = 2[((A-B)/CD+1)6-1]

  Where:

          a  =dividends and interest earned during the period.
          b  =expenses accrued for the period (net of reimbursements).
          c  =the average daily number of shares outstanding during
              the period that were entitled to receive dividends.
          d  =the maximum offering price per share on the last day of
              the period.

                          INVESTMENT ADVISORY SERVICES

The Fund employs Mellon Capital  Management  Corporation  (Mellon Capital),  595
Market St., Suite 3000, San Francisco,  California  94105 (the Adviser) under an
investment  advisory  agreement to manage the investment and reinvestment of the
assets of the Fund and to  continuously  review,  supervise and  administer  the
Fund's investment program. The Adviser discharges its  responsibilities  subject
to the control of the officers and Board of Trustees of the Fund.

     The Fund pays the  Adviser a Basic fee at the end of each  fiscal  quarter,
calculated  by  applying  a  quarterly  rate,  based  on  the  following  annual
percentage rates, to the Fund's average month-end net assets for the quarter:

     NET ASSETS                         ANNUAL RATE
     ----------                         -----------
     First $100 million......               0.200%
     Next $900 million.......               0.150%
     Next $500 million.......               0.125%
     Over $1.5 billion.......               0.100%

  This fee may be increased or decreased by applying an adjustment formula based
on the performance of the Fund's portfolio  relative to the investment record of
a "Combined Index", 65% of which shall be comprised of the Standard & Poor's 500
Composite Price Index and 35% of which shall be comprised of the Lehman Brothers
Long-Term U.S. Treasury Index. The fee payment will be increased  (decreased) by
an incentive  (penalty) of 0.05% of average net assets, if the Fund's cumulative
investment  performance  for  the  thirty-six  months  preceding  the end of the
quarter  is  at  least  six  percentage  points  above  (below)  the  cumulative
investment record of the Combined Index for the same period.  For the purpose of
determining the fee adjustment for investment  performance,  as described above,
the net  assets  of the  Fund  will be  averaged  over the  same  period  as the
performance  of the Fund and the  investment  record of the  Combined  Index are
computed.

  Under  the  rules  of  the  Securities  and  Exchange   Commission,   the  new
incentive/penalty  fee will not be fully operable until the quarter ending March
31,  2000.  Until  that  date,  a  "blended"  fee  rate  consisting  of  varying
percentages of (i) the  performance  adjustment  based on the schedule set forth
above  (the  "New  Rate"1),  and (ii) the  performance  adjustment  based on the
schedule set forth in the Fund's previous investment advisory agreement with the
adviser2 (the "Previous Rate") shall be used as follows:

1. Quarter Ending June 30, 1997. The incentive/penalty fee was calculated as the
sum of 8.3% (e.g.,  one of 12  quarters)  of the fee payable  under the New Rate
plus 91.7% (e.g., 11 of 12 quarters) of the fee payable under the Previous Rate.

2. Quarter Ending September 30, 1997. The  incentive/penalty  fee was calculated
as the sum of 16.6% of the fee payable  under the New Rate plus 83.4% of the fee
payable under the Previous Rate.

                                      B-17
<PAGE>

3. Quarter Ending December 31, 1997. The incentive/penalty fee was calculated as
the sum of 25% of the fee payable under the New Rate plus 75% of the fee payable
under the Previous Rate.

4. Quarter  Ending March 31, 1998. The  incentive/penalty  fee was calculated as
the sum of 33.3% of the fee  payable  under the New Rate  plus  66.7% of the fee
payable under the Previous Rate.

5. Quarter Ending June 30, 1998. The incentive/penalty fee was calculated as the
sum of 41.6% of the fee payable under the New Rate plus 58.4% of the fee payable
under the Previous Rate.

6. Quarter Ending September 30, 1998. The  incentive/penalty  fee was calculated
as the sum of 50% of the fee  payable  under  the New  Rate  plus 50% of the fee
payable under the Previous Rate.

7. Quarter Ending December 31, 1998. The incentive/penalty fee was calculated as
the sum of 58.4% of the fee  payable  under the New Rate  plus  41.6% of the fee
payable under the Previous Rate.

8. Quarter  Ending March 31, 1999. The  incentive/penalty  fee was calculated as
the sum of 66.7% of the fee  payable  under the New Rate  plus  33.3% of the fee
payable under the Previous Rate.

9. Quarter Ending June 30, 1999. The incentive/penalty fee was calculated as the
sum of 75% of the fee  payable  under the New Rate  plus 25% of the fee  payable
under the Previous Rate.

10. Quarter Ending September 30, 1999. The  incentive/penalty fee was calculated
as the sum of 83.4% of the fee payable  under the New Rate plus 16.6% of the fee
payable under the Previous Rate.

11. Quarter Ending December 31, 1999. The  incentive/penalty  fee was calculated
as the sum of 91.7% of the fee  payable  under the New Rate plus 8.3% of the fee
payable under the Previous Rate.

12. Quarter Ending March 31, 2000. New Rate fully operable.


     For  the  purpose  of   determining   the  fee  adjustment  for  investment
performance,  as described  above,  the net assets of the Fund shall be averaged
over  the  same  period  as the  investment  performance  of the  Fund  and  the
investment   record  of  the  Combined  Index  are  computed.   The  "investment
performance" of the Fund for the period, expressed as a percentage of the Fund's
net asset value per share at the beginning of the period. The benchmark used for
the new rate  calculation  will  consist  of  linking  the  return  of the "new"
benchmark  (a  "Combined  Index",  65% of which is  comprised  of the Standard &
Poor's 500  Composite  Price Index and 35% of which is  comprised  of the Lehman
Brothers  Long-Term  U.S.  Treasury  Index)  to the  return  of  the  "previous"
benchmark  (Standard & Poor's 500  Composite  Price  Index) in the same  varying
percentages  that  are  listed  below.     The  previous  incentive/penalty  fee
structure  provided  that the Basic Fee be  increased  or decreased by an amount
equal  to 0.05%  of the  average  month-end  assets  of the  Fund if the  Fund's
investment  performance  for  the  thirty-six  months  preceding  the end of the
quarter  was six  percentage  points or more above or below,  respectively,  the
investment  record of the Standard & Poor's 500 Composite Price Index.  shall be
the sum of: (i) the change in the Fund's net asset  value per share  during such
period;  (ii) the value of the Fund's  cash  distributions  per share  having an
ex-dividend date occurring within the period;  and (iii) the per share amount of
capital  gains  taxes  paid or  accrued  during  such  period  by the  Fund  for
undistributed realized long-term capital gains.


     The "investment  record" of the Stock Index for the period,  expressed as a
percentage of the Stock Index level at the beginning of the period, shall be the
sum of (i) the change in the level of the Stock Index during the period and (ii)
the value,  computed  consistently  with the Stock Index, of cash  distributions
having an ex-dividend  date occurring  within the period made by companies whose
securities  comprise the Stock Index. The "investment  record" of the Bond Index
for the  period,  expressed  as a  percentage  of the  Bond  Index  level at the
beginning  of such period shall be the sum of (i) the change in the level of the
Bond Index during the period and (ii) the value of the interest  accrued or paid
on the bonds  included  in the Bond Index,  assuming  the  reinvestment  of such
interest on a monthly basis. Computation of these two components as the Combined
Index  shall be made on the basis of 65% in the Stock  Index and 35% in the Bond
Index at the beginning of each quarter.


     The investment advisory agreement will be renewable for successive one-year
periods,  only if each renewal is specifically  approved by a vote of the Fund's
Board of Trustees, including the affirmative votes of a majority of the Trustees
who are not parties to the contract or  "interested

                                      B-18
<PAGE>

persons"  (as  defined in the 1940 Act) of any such  party,  cast in person at a
meeting  called for the purpose of considering  such approval.  The agreement is
automatically  terminated if assigned,  and may be terminated without penalty at
any time:


(1)  either  by vote of the  Board  of  Trustees  of the  Fund or by vote of its
outstanding voting securities on 60 days' written notice to the Adviser, or

(2) by the Adviser upon 90 days' written notice to the Fund.

The Fund's Board of Trustees may, without the approval of shareholders,  provide
for:

 . The  employment  of a new  investment  adviser  pursuant to the terms of a new
  advisory  agreement,  either as a replacement for an existing adviser or as an
  additional adviser.

 . A change in the terms of an advisory agreement.

 . The continued  employment of an existing adviser on the same advisory contract
  terms where a contract has been assigned because of a change in control of the
  adviser. Any such change will be communicated to shareholders in writing.



     DESCRIPTION OF THE ADVISER.  The Adviser is an investment  management  firm
which  manages well  diversified  stock and bond  portfolios  for  institutional
clients.  As of  September  30, 1999 the Adviser  provided  investment  advisory
services  to 270 clients and  managed  assets with an  approximate  value of $73
billion.  The Adviser's asset allocation strategy was developed by the Adviser's
co-founder,  William  Fouse,  in  1972,  and is used by 134 of its  clients  and
accounts  for  approximately  $30  billion of the assets  that it  manages.  The
Adviser is a wholly-owned subsidiary of MBC Investment Corporation, which itself
is a wholly-owned  subsidiary of Mellon  Financial  Corporation.  For the fiscal
years ended September 30, 1997, 1998, and 1999, the Fund incurred  approximately
$3,723,000  (before a decrease of  $921,000  based on  performance),  $5,466,000
(before a decrease of $1,404,000 based on performance) and $8,336,000  (before a
decrease of $1,564,000)  respectively,  for investment  advisory  services.


                             PORTFOLIO TRANSACTIONS

The investment  advisory agreement  authorizes the Adviser (with the approval of
the Fund's Board of Trustees) to select the brokers or dealers that will execute
the  purchases  and sales of portfolio  securities  for the Fund and directs the
Adviser  to use its best  efforts to obtain  the best  available  price and most
favorable  execution as to all transactions for the Fund. The Adviser undertakes
to execute each investment  transaction at a price and commission which provides
the most  favorable  total  cost or  proceeds  reasonably  obtainable  under the
circumstances.
  In placing portfolio  transactions,  the Adviser will use its best judgment to
choose the broker most capable of providing the brokerage  services necessary to
obtain best  available  price and most favorable  execution.  The full range and
quality of  brokerage  services  available  will be  considered  in making these
determinations.  In those instances where it is reasonably  determined that more
than one  broker  can offer the  brokerage  services  needed to obtain  the best
available price and most favorable  execution,  consideration  may be  given  to
those brokers which supply investment  research and  statistical information and
provide other services in addition  to  execution  services to the Fund  and/ or
the  Adviser.  The Adviser considers such  information useful in the performance
of its obligations  under the agreement,  but is unable to determine the  amount
by which such services may reduce its expenses.
  The investment  advisory  agreement also  incorporates the concepts of Section
28(e) of the Securities  Exchange Act of 1934 by providing that,  subject to the
approval of the Fund's Board of Trustees,  the Adviser may cause the Fund to pay
a  broker-dealer  which  furnishes  brokerage  and  research  services  a higher
commission  than that  which  might be  charged  by  another  broker-dealer  for
effecting  the  same  transaction;  provided  that  such  commission  is  deemed
reasonable  in  terms of  either  that  particular  transaction  or the  overall
responsibilities of the Adviser to the Fund.
  Currently,  it is the Fund's  policy  that the Adviser may at times pay higher
commissions  in  recognition  of  brokerage  services  felt  necessary  for  the
achievement  of  better  execution  of  certain

                                      B-19
<PAGE>

securities transactions that otherwise might not be available.  The Adviser will
only pay such higher  commissions if it believes this to be in the best interest
of the Fund. Some brokers or dealers who may receive such higher  commissions in
recognition   of  brokerage   services   related  to  execution  of   securities
transactions  are also  providers of research  information to the Adviser and/or
the Fund.
  The total  brokerage  commissions  paid by the Fund for the fiscal years ended
September 30, 1997,  1998, and 1999,  totaled  $113,938,  $96,955,  and  $90,273
respectively.
  Some securities  considered for investment by the Fund may also be appropriate
for other  clients  served by the Adviser.  If purchases or sales of  securities
consistent  with the  investment  policies  of the Fund and one or more of these
other clients  serviced by the Adviser are considered at or about the same time,
transactions  in such securities will be allocated among the Fund and such other
clients in a manner deemed equitable by  the Adviser.   Although there may be no
specified formula for allocating such transactions, the allocation methods used,
and the results of such allocations,  will be subject  to periodic review by the
Fund's Board of Trustees.


                                    GLOSSARY

a. HISTORICAL  MARKET RETURNS -- Total returns of broad asset class  benchmarks.
   As examples, the returns of well-known benchmarks for domestic stocks, bonds,
   and money market instruments are given below.

                                                                 MONEY MARKET
ASSET CLASS        COMMON STOCKS              BONDS              INSTRUMENTS
              STANDARD & POOR'S 500
              COMPOSITE STOCK PRICE   LEHMAN BROTHERS LONG  90 DAY U.S. TREASURY
 BENCHMARK            INDEX              TREASURY INDEX            BILLS
- --------------------------------------------------------------------------------
  1989                 31.6%                  18.9%                    8.6%
  1990                 -3.1                    6.3                     7.9
  1991                 30.4                   18.5                     5.8
  1992                  7.6                    8.0                     3.6
  1993                 10.1                   17.3                     3.1
  1994                  1.3                   -7.6                     4.2
  1995                 37.6                   30.7                     5.8
  1996                 23.0                   -0.9                     5.2
  1997                 29.6                    8.1                     3.9
  1998 (9/30)           9.1                   22.1                     5.2

b. ASSET  ALLOCATION -- Asset  allocation -- in its most generic sense -- is the
   allotment of an  investor's  monies to broad asset  classes such as stocks or
   bonds.  Investors  establish  percentage  allocation  guidelines  for stocks,
   bonds,  and  money  market   instruments  which  are  consistent  with  their
   particular  long-term  investment  needs.  These needs will  include  current
   income, potential growth in capital, and willingness to accept risk.

     In implementing their asset allocation  targets,  some investors attempt to
maintain a stable mix -- such as 50% stocks and 50% bonds -- while  others  will
actively manage the stock/bond mix in pursuit of higher returns,  lower risk, or
other investment objectives. The key difference between investors who maintain a
stable mix and those who actively  change  allocations  is their  willingness to
forecast the risks and returns of individual  asset classes,  their  forecasting
abilities,  and their  comfort in making  investment  decisions  based upon such
forecasts.  Historically,  investors  who  actively  managed  the mix based upon
conjecture  have often  underperformed  both  investors with  relatively  stable
allocations  and  investors  with  logical,  disciplined  methods for  assessing
relative value and risk.  Institutional investors commonly refer to active asset
allocation approaches which are based upon disciplined methodologies as tactical
asset allocation.

                                      B-20
<PAGE>

                              FINANCIAL STATEMENTS

The Fund's financial statements,  including the financial highlights for each of
the five fiscal years in the period ended  September 30, 1999,  appearing in the
Fund's  1999  Annual  Report  to   Shareholders   and  the  report   thereon  of
PricewaterhouseCoopers LLP, independent accountants, also appearing therein, are
incorporated by reference into this Statement of Additional  Information.  For a
more complete discussion of the performance, please see the Fund's Annual Report
to Shareholders, which may be obtained without charge.


                                      B-21

<PAGE>


                                                                          SAI078


                                      B-22

<PAGE>




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