AMERICAN CENTURY MUNICIPAL TRUST
N-30D, 1998-01-30
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                                  SEMIANNUAL
                                    REPORT

                            [american century logo]
                                    American
                                Century(reg.sm)


                               NOVEMBER 30, 1997

                                    BENHAM
                                     GROUP

                        Florida Municipal Money Market
                      Florida Intermediate-Term Municipal

                               TABLE OF CONTENTS

Report Highlights .........................................................    1
Our Message to You ........................................................    2
Market Perspective ........................................................    3
Florida Municipal Money Market
           Performance & Portfolio Information ............................    4
           Management Q & A ...............................................    5
           Schedule of Investments ........................................    7
           Financial Highlights ...........................................   21
Florida Intermediate-Term Municipal
           Performance & Portfolio Information ............................    9
           Management Q & A ...............................................   10
           Schedule of Investments ........................................   13
           Financial Highlights ...........................................   22
Statements of Assets and Liabilities ......................................   15
Statements of Operations ..................................................   16
Statements of Changes in Net Assets .......................................   17
Notes to Financial Statements .............................................   18
Proxy Voting Results ......................................................   23
Background Information
           Investment Philosophy & Policies ...............................   24
           Comparative Indices ............................................   24
           Lipper Rankings ................................................   24
           Investment Team Leaders ........................................   24
Glossary ..................................................................   25

       American Century  Investments  offers you nearly 70 fund choices covering
stocks,  bonds,  money markets,  specialty  investments and blended  portfolios.
We've organized our funds into three distinct groups,  based on investment style
and objectives, to help simplify your fund decisions. These groups appear below.


                  AMERICAN CENTURY INVESTMENTS--FAMILY OF FUNDS
- -------------------------------------------------------------------------------
        Benham                American Century       Twentieth Century(reg. tm)
     Group(reg. tm)                 Group                      Group
- -------------------------------------------------------------------------------
   MONEY MARKET FUNDS         ASSET ALLOCATION &           GROWTH FUNDS
 GOVERNMENT BOND FUNDS          BALANCED FUNDS          INTERNATIONAL FUNDS
 DIVERSIFIED BOND FUNDS   CONSERVATIVE EQUITY FUNDS
  MUNICIPAL BOND FUNDS         SPECIALTY FUNDS
- -------------------------------------------------------------------------------
  Florida Municipal
    Money Market

 Florida Intermediate-
    Term Municipal

We welcome your comments or questions about this report.  
See the back cover for ways to contact us by mail, phone or e-mail.

Twentieth  Century and American Century are registered marks of American Century
Services  Corporation.  Benham Group is a registered  mark of Benham  Management
Corporation.


                                                AMERICAN CENTURY INVESTMENTS


                               REPORT HIGHLIGHTS

MARKET PERSPECTIVE

*   Municipal  securities  produced  solid  returns  during the six months ended
    November 30, 1997.

*   Despite lower yields overall, low unemployment and rising wages sparked bond
    market volatility.

*   Credit spreads fell to historically  low levels because of improving  credit
    quality and the increase in the number of municipal  securities insured with
    a AAA rating.

MUNICIPAL CREDIT REVIEW

*   Continued   strong  economic  growth  coupled  with  fiscally   conservative
    budgeting practices  contributed to a generally positive outlook for Florida
    municipal credit quality.

*   Nevertheless,  the  state  is  likely  to face  large  capital  outlays  for
    education and infrastructure going forward.

FLORIDA TAX-FREE MONEY MARKET

*   The fund  outperformed the average state tax-exempt money market fund during
    the six months ended November 30, 1997.

*   We've limited the fund's  exposure to Japanese  banks,  which provide credit
    backing for many municipal money market securities.

*   Going forward,  we'll continue to use a value-oriented  approach to security
    selection,  buying  one-year  notes when we think they provide  sufficiently
    higher yields than shorter-term securities.

FLORIDA INTERMEDIATE-TERM MUNICIPAL

*   The fund strongly  outperformed both its Lipper peer group and benchmark for
    the six months.

*   For the year  ended  November  30,  1997,  the fund was  ranked #1 out of 20
    Florida  intermediate  municipal debt funds,  according to Lipper Analytical
    Services.

*   Below-average  expenses,  good  duration  management  and  careful  security
    selection were key reasons for the fund's strong returns.

*   Going forward,  we'll  continue to take a conservative  approach to security
    selection and managing the fund's duration.


              FLORIDA MUNICIPAL
                MONEY MARKET

TOTAL RETURNS:             AS OF 11/30/97
     6 Months                      1.66%*
     1 Year                          3.42%

7-DAY CURRENT YIELD:                 3.55%

NET ASSETS:                 $80.4 million
     (AS OF 11/30/97)

INCEPTION DATE:                    4/11/94

TICKER SYMBOL:                       BEFXX


                   FLORIDA
            INTERMEDIATE-TERM MUNICIPAL

TOTAL RETURNS:             AS OF 11/30/97
     6 Months                      4.73%*
     1 Year                          6.78%

30-DAY SEC YIELD:                    4.02%

NET ASSETS:                 $20.6 million
     (AS OF 11/30/97)

INCEPTION DATE:                    4/11/94

TICKER SYMBOL:                       ACBFX

* Not annualized.

Many of the investment  terms in this report are defined in the Glossary on page
25.


SEMIANNUAL REPORT                                 REPORT HIGHLIGHTS       1


                              OUR MESSAGE TO YOU

              [photo of James E. Stowers III and James M. Benham]

    The Benham  Florida  Municipal  funds  performed  well during the six months
ended November 30, 1997, rewarding investors with  better-than-average  returns.
Healthy U.S.  economic  growth  coupled with low inflation  provided a favorable
backdrop for strong municipal bond  performance.  Our municipal  investment team
provides  details  on  market  conditions  and your  fund's  performance  on the
following pages.

    On the  corporate  front,  the latter half of 1997  proved as  eventful  for
American  Century as it was for  investors.  In July,  J.P.  Morgan & Co.,  Inc.
agreed to become a significant minority shareholder in our company. Through this
business  partnership,  we  see  many  opportunities  to  expand  the  range  of
investment  choices and services we offer you. J.P.  Morgan has been in business
for more than 150 years, serving institutions,  governments and individuals with
complex  financial needs.  Within the framework of this  relationship,  American
Century  will  continue  to operate as an  independent  company.  Our  corporate
management  team will remain the same, and the Stowers family will retain voting
control of the company.

    On a more  personal  note,  1997 was the year we said  farewell  to James M.
Benham,  founder of the Benham Group of mutual funds. Mr. Benham,  who announced
his  retirement in December,  was a pioneer in the no-load  mutual fund industry
and the father of Capital  Preservation  Fund,  the first money  market fund for
individual  investors.  With the  integration  of Benham and  Twentieth  Century
successfully  completed,  Mr.  Benham  felt it was  time to step  back  from the
business and enjoy a well-earned retirement,  confident that he leaves the funds
he founded in very  capable  hands.  Though his  counsel  and  guidance  will be
missed,  much of the  Benham  culture  has  become a part of  American  Century,
including the educational  investor seminar program Mr. Benham created.  And two
of his sons,  Jim A. Benham and Tim Benham,  remain with the company to carry on
the Benham tradition.

    Looking  forward,  1998 will be a  landmark  year for us,  marking  the 40th
anniversary of the introduction of our first two funds, Twentieth Century Growth
and  Twentieth  Century  Select.  Not many fund  companies  have a 40-year track
record, nor have many built a fund family such as ours, which includes nearly 70
stock,  bond,  money and  combination  funds that provide  investors with a wide
range of choice and flexibility.

    Whatever your financial  goals, we believe we have an outstanding  lineup of
funds to help you pursue them.

    Sincerely,

/s/James E. Stowers III                  /s/James M. Benham
James E. Stowers III                     James M. Benham
Chief Executive Officer                  Vice Chairman
American Century Investment              American Century Investment
   Management, Inc.                         Management, Inc


2      OUR MESSAGE TO YOU                     AMERICAN CENTURY INVESTMENTS


                              MARKET PERSPECTIVE

[line graph - data below]

MUNICIPAL YIELD CURVES

Years to Maturity          11/30/97               5/31/97
1                           3.690%                3.850%
2                           3.840%                4.150%
3                           3.960%                4.350%
4                           4.070%                4.500%
5                           4.170%                4.600%
6                           4.260%                4.660%
7                           4.350%                4.720%
8                           4.430%                4.780%
9                           4.510%                4.840%
10                          4.590%                4.900%
11                          4.666%                4.976%
12                          4.742%                5.052%
13                          4.818%                5.128%
14                          4.894%                5.204%
15                          4.970%                5.280%
16                          5.000%                5.308%
17                          5.030%                5.336%
18                          5.060%                5.364%
19                          5.090%                5.392%
20                          5.120%                5.420%
21                          5.126%                5.426%
22                          5.132%                5.432%
23                          5.138%                5.438%
24                          5.144%                5.444%
25                          5.150%                5.450%
26                          5.154%                5.454%
27                          5.158%                5.458%
28                          5.162%                5.462%
29                          5.166%                5.466%
30                          5.170%                5.470%

Source: Bloomberg Financial Markets


SOLID MUNICIPAL BOND RETURNS

    Municipal securities produced very solid returns during the six months ended
November 30, 1997. As the accompanying  graph indicates,  yields fell across the
maturity spectrum.

    For the period, the Lehman Brothers Long-Term  Municipal Bond Index returned
6.90%.  Intermediate-term securities,  represented by the Lehman Brothers 5-Year
Municipal General Obligation Index, returned 4.04%. The short-term Merrill Lynch
0- to 3-Year Municipal Index posted a 2.62% return.

INCREASED MARKET VOLATILITY

    Despite lower interest rates overall, municipal yields fluctuated throughout
the period.  Uncertainty  in the bond market over how long  inflation can remain
tame with the  unemployment  rate so low was  largely  responsible  for the rate
fluctuations.  Low  unemployment  has  led  to  inflation  in the  past  because
companies tend to raise wages in an attempt to keep or hire  employees.  Because
wages  account for about  two-thirds of all business  costs,  higher wages often
lead to inflation.

    But despite a November  1997  unemployment  rate of  4.6%--the  lowest in 24
years--and signs of rising wages, overall inflation remained low. Inflation,  as
measured by the  government's  consumer  price  index,  rose at the slowest pace
since 1986 for the first 11 months of calendar 1997.

    Increased  productivity  was a key reason wages could rise without  sparking
inflation, as businesses reaped the rewards of huge investments in computers and
other productivity tools. According to the Labor Department,  productivity gains
in the third quarter of 1997 were the fastest in five years.

    Turmoil in Asian financial markets also contributed to lower yields and U.S.
bond market  volatility.  Weakness in Asia caused huge cash flows to move in and
out of U.S. Treasury securities,  which are considered "safe-haven" investments.
Because  demand for  municipal  securities  is often  predicated on the relative
prices of municipals and Treasurys,  big swings in the Treasury market can carry
over to the municipal market.

IMPACT OF BOND INSURANCE

    An  increase  in the  amount  of  debt  being  issued  with  bond  insurance
contributed to a narrower  spread,  or difference in yield,  between AAA and BBB
securities.

    About  60% of all  municipal  debt now comes to  market  insured  with a AAA
rating.  That has boosted credit quality generally by dramatically  reducing the
amount of paper issued at the lower investment grades. But it has also increased
demand for a shrinking supply of lower-rated,  higher-yielding  paper.  Combined
with the  improvement  in credit quality  generally,  the net effect has been to
push credit spreads to historically low levels.


SEMIANNUAL REPORT                                MARKET PERSPECTIVE       3


<TABLE>
<CAPTION>
                        FLORIDA MUNICIPAL MONEY MARKET

                       7-DAY           7-DAY                         7-DAY TAX-EQUIVALENT YIELDS
                      CURRENT        EFFECTIVE          28%              31%             36%              39.6%
                       YIELD           YIELD        Tax Bracket      Tax Bracket     Tax Bracket       Tax Bracket
- ----------------------------------------------------------------------------------------------------------------------
YIELDS AS OF
NOVEMBER 30, 1997

Florida Municipal
<S>                    <C>             <C>             <C>              <C>             <C>               <C>  
Money Market           3.55%           3.61%           4.93%            5.14%           5.55%             5.88%


                                                                         AVERAGE ANNUAL RETURNS
                                     6 MONTHS          1 YEAR          3 YEARS       LIFE OF
FUND(1)
- ---------------------------------------------------------------------------------------------------------------------
TOTAL RETURNS AS OF
NOVEMBER 30, 1997(2)

Florida Municipal Money Market ....... 1.66%           3.42%           3.72%         3.63%

Average Other States Tax-Exempt
   Money Market Fund(3) .............. 1.63%           3.22%           3.32%         3.23%(4)

Fund's Ranking Among Other States
Tax-Exempt Money Market Funds(3) .....  --          7 out of 33     1 out of 26     1 out of 17(4)
</TABLE>
- ----------

(1)  Inception date was April 11, 1994.

(2)  Returns for periods less than one year are not annualized.

(3)  According to Lipper Analytical Services.

(4)  Returns from 4/30/94,  the date nearest the fund's inception for which data
     are available.

See pages 24-25 for more information about returns and Lipper fund rankings.


PORTFOLIO AT A GLANCE
                                11/30/97         5/31/97
Number of Securities               41              50
Weighted Average Maturity        64 days         48 days
Expense Ratio                   0.53%(1)        0.12%(2)

(1)  Annualized.

(2)  Until December 31, 1996, the fund's  management  fees were waived by Benham
     Management  Corporation (BMC). As of January 1, 1997,  management fees were
     phased in at a rate of 0.10% each month until a rate of 0.61% was  reached.
     Had fees not been waived, returns would have been lower.

Money market funds are neither insured nor guaranteed by the U.S. government.

Yields will fluctuate,  and there can be no assurance that the fund will be able
to maintain a stable $1.00 share price.

Past performance is no guarantee of future results.


4      FLORIDA MUNICIPAL MONEY MARKET         AMERICAN CENTURY INVESTMENTS


                        FLORIDA MUNICIPAL MONEY MARKET

MANAGEMENT Q & A

    An  interview  with  Bryan  Karcher,  a  portfolio  manager  on the  Florida
Municipal Money Market fund investment team.

HOW DID THE FUND PERFORM?

    The fund  continued  to provide a higher  level of tax-free  income than the
average state  tax-exempt  money market fund.  For the six months ended November
30, 1997, the fund had a total return of 1.66%,  compared with the 1.63% average
return  of the 33  "State  Tax-Exempt  Money  Market  Funds"  tracked  by Lipper
Analytical Services. (See the Total Returns table on the previous page for other
fund performance comparisons.)

HOW DID YOU POSITION THE FUND DURING THE PERIOD?

    Finding  longer-maturity,  higher-yielding  securities was difficult because
short-term  securities had almost the same yields as longer-term  securities for
much of the period.  Inflation  remained under control,  and the likelihood that
the Federal Reserve would raise interest rates diminished. That caused the yield
curve  between  three  months and one year to  flatten--the  yields on  one-year
Treasury notes dropped,  bringing the spread  between  three-month  and one-year
Treasurys to 25 basis points, or 0.25%.

    As a result,  we allowed the fund's average maturity to shorten to around 30
days in  September,  rather than  purchase  one-year  notes that we felt weren't
offering  sufficiently  higher  yields than  shorter-term  securities.  However,
one-year  notes began to look more  attractive  in October and  November,  so we
extended the fund's average maturity out beyond 60 days.

HOW DO YOU DECIDE WHEN A ONE-YEAR SECURITY IS A GOOD BUY?

    First,  we  look  at  how  much  additional  yield  we  anticipate  one-year
securities will offer versus weekly  variable-rate  notes (floaters),  given our
outlook for interest rates.  That helps us determine if we're being  compensated
with enough  additional yield to justify  extending the fund's average maturity.
Second,  we look at the relative  value of one-year  municipal  securities  as a
percentage of Treasurys. This provides a second measure of the attractiveness of
one-year  municipal  paper.  We know one-year  paper is more likely to be a good
value when both of these  indicators  are positive,  as they were in October and
November.

THE FUND'S  MANAGEMENT FEE WAS LOWERED  DURING THE PERIOD.  HOW WILL THAT AFFECT
THE FUND?

    We lowered the fund's expenses on August 1, 1997, from 61 to 50 basis points
(from 0.61% to 0.50%),  which puts us among the lowest-cost Florida money market
funds.  The new,  lower expenses  directly  benefit  shareholders  because we're
delivering the same strong performance,  but at a lower cost. Other things being
equal, lower expenses mean higher returns and yields for our shareholders.

[pie charts]

PORTFOLIO COMPOSITION BY SECURITY TYPE (as of 11/30/97)
VRDNs                      67%
Bonds less than 1 Year     12%
Commercial Paper            5%
Municipal Notes             4%
Other                      12%

PORTFOLIO COMPOSITION BY SECURITY TYPE (as of 5/31/97)
VRDNs             63%
Bonds 
 Less Than 1 Year 18%
Commercial Paper  16%
Municipal Notes   3%


SEMIANNUAL REPORT                   FLORIDA MUNICIPAL MONEY MARKET        5


                        FLORIDA MUNICIPAL MONEY MARKET

HOW DO JAPANESE BANKS AFFECT THE FUND'S PORTFOLIO?

    Many  municipal  money  market  securities  are  backed by letters of credit
(LOCs) issued by banks,  including  Japanese banks. Over the last several years,
the Japanese banking system has suffered from a lengthy  domestic  recession and
non-performing real estate loans.

    Consistent with our strict municipal credit criteria,  over the last year we
reduced the number of Japanese banks whose  obligations we approve for purchase.
As of  December,  Bank of  Tokyo/Mitsubishi  was the only  Japanese  bank  whose
securities we continued to hold.  We anticipate  that we will no longer have any
Japanese bank exposure after February 1998.

    Currently,  the only  securities  backed by Japanese banks that we hold have
maturities  of 7 days or less.  That  means  we can get out of these  securities
quickly if our credit  outlook for Japanese  banks should  change.  In addition,
we've established  credit standards that prevent the fund from holding more than
5% of its assets in securities guaranteed by Japanese banks.

WHAT'S YOUR OUTLOOK FOR INTEREST RATES GOING FORWARD?

    We think the outlook for interest rates is relatively stable. The economy is
fairly strong,  but inflation remains low, so we don't see a strong call for Fed
action on interest  rates  either way in the near  future.  However,  supply and
demand  factors in the  municipal  money  market seem to argue for lower  yields
after year's end. The first  quarter  tends to bring lower yields  because there
are many buyers in the market at a time when there is little new issuance.  As a
result,  yields for tax-free  money market funds tend to drop,  particularly  in
January.

HOW WILL YOU MANAGE THE FUND OVER THE NEXT SIX MONTHS?

    We'll  continue to use a  value-oriented  approach  to  security  selection,
monitoring the relative values of one-year notes and shorter-term securities. We
also  anticipate  large cash inflows in December from investors  eager to reduce
their exposure to Florida's  intangibles tax. We typically put that new money to
work in daily or weekly floaters. We buy floaters,  which mature quickly and are
relatively  easy to buy and sell,  because a lot of that money flows back out of
the fund in January.

[pie charts]

PORTFOLIO COMPOSITION BY CREDIT RATING (as of 11/30/97)
SP1+              76%
SP1               24%

PORTFOLIO COMPOSITION BY CREDIT RATING (as of 5/31/97)
SP1+              75%
SP1               25%


6      FLORIDA MUNICIPAL MONEY MARKET         AMERICAN CENTURY INVESTMENTS


<TABLE>
<CAPTION>
                            SCHEDULE OF INVESTMENTS
                        FLORIDA MUNICIPAL MONEY MARKET

NOVEMBER 30, 1997 (UNAUDITED)


Principal Amount                                                            Value
- --------------------------------------------------------------------------------------

SHORT-TERM MUNICIPAL SECURITIES

<S>             <C>                                                   <C>                                 
                $1,000,000  Alachua County Industrial
                                Development Rev., (Florida Rock
                                Industries Income Project),
                                VRDN, 4.00%, 12/4/97 (LOC:
                                Bank of America N.T. & S.A.)           $  1,000,000

                   550,000  Broward County Housing Finance
                                Auth. Multi-Family Housing Rev.,
                                Series 1990 A, (Palm Aire
                                Oxford), VRDN, 4.20%, 12/3/97
                                (SBBPA: Continental Casualty Co.)           550,000

                 3,250,000  Broward County Housing Finance
                                Auth. Single-Family Mortgage
                                Rev., Series 1997 B, 4.05%,
                                4/1/98 (GIC: GE Capital
                                Corporation)                              3,250,000

                 1,270,000  Broward County Industrial
                                Development Rev., (Fast Real
                                Estate Partners),  VRDN, 4.05%,
                                12/3/97 (LOC: Suntrust Bank
                                South Florida, N.A.)                      1,270,000

                 2,500,000  Broward County Industrial Development Rev.,
                                (HEICO), VRDN, 4.05%, 12/3/97 (LOC:
                                Suntrust Bank South Florida, N.A.)        2,500,000

                 2,420,000  Broward County Industrial
                                Development Rev., (MDR Fitness
                                Project), VRDN, 4.05%, 12/3/97
                                (LOC: Suntrust Bank, Miami, N.A.)         2,420,000

                 3,000,000  Broward County School District
                                Rev., Series 1997 C, 4.50%,
                                4/22/98                                   3,006,396

                 2,745,000  Collier County Housing Finance
                                Auth. Multi-Family Rev., (Saxon
                                Manor Isles Project), VRDN,
                                3.85%, 12/3/97 (LOC: PNC
                                Bank, Kentucky Inc.)                      2,745,000

                 1,860,000  Coral Springs Industrial
                                Development Rev., (Royal
                                Plastics Group Project), VRDN,
                                4.05%, 12/3/97 (LOC: Suntrust
                                Bank South Florida, N.A.)                 1,860,000

                 3,000,000  Dade County Housing Finance
                                Auth. Single-Family Rev., Series
                                1997 C, 4.05%, 10/16/98
                                (GIC: FGIC)                               3,000,000


Principal Amount                                                            Value
- --------------------------------------------------------------------------------------

                $4,495,000  Dade County Industrial
                                Development Auth. Rev., (IVAX
                                Labs), VRDN, 4.30%, 12/3/97
                                (LOC: Bank of Tokyo-Mitsubishi,
                                Ltd.)                                  $  4,495,000

                 1,000,000  Dade County Industrial
                                Development Auth. Rev.,
                                (Stephen M. Greene), VRDN,
                                4.15%, 12/3/97 (LOC: Suntrust
                                Bank, Miami, N.A.)                        1,000,000

                 3,295,000  Dade County Special Obligation Capital Asset
                                Acquisition Rev., VRDN, 4.30%, 12/3/97 (LOC:
                                Sanwa Bank Ltd.)                          3,295,000

                 1,965,000  Escambia County Housing Finance
                                Auth. Single-Family Mortgage
                                Rev., VRDN, 4.10%, 12/4/97
                                (SBBPA: Merrill Lynch & Co. Inc.)         1,965,000

                 2,125,000  Florida Board of Education
                                Capital Outlay GO, 6.60%,
                                6/1/98                                    2,154,306

                   500,000  Florida Board of Education Capital Outlay GO,
                                Series 1995 B, 5.625%,
                                6/1/98                                      504,039

                 2,720,000  Florida Department of Transportation
                                GO, Series 1997 A, 6.40%,
                                7/1/98                                    2,760,387

                 4,650,000  Florida Housing Finance Agency Rev., (Ashley
                                Lakes Project), VRDN, 3.95%, 12/3/97 (LOC:
                                Barclays Bank PLC)                        4,650,000

                 1,200,000  Florida Housing Finance Agency
                                Rev., (Belville-Oxford), VRDN,
                                4.20%, 12/3/97 (SBBPA:
                                Continental Casualty Co.)                 1,200,000

                 4,500,000  Florida Housing Finance Agency Rev., (Caribbean
                                Key), VRDN, 4.00%, 12/3/97 (LOC:
                                KeyBank, N.A.)                            4,500,000

                 3,800,000  Florida Housing Finance Agency
                                Rev., (Country Club Apartments),
                                VRDN, 4.10%, 12/1/97 (LOC:
                                Northern Trust Corp.)                     3,800,000

                 2,500,000  Florida Housing Finance Agency Rev., (Heron Park
                                Project), VRDN, 3.95%, 12/3/97 (LOC:
                                NationsBank N.A.)                         2,500,000

See Notes to Financial Statements


SEMIANNUAL REPORT                   FLORIDA MUNICIPAL MONEY MARKET        7


                            SCHEDULE OF INVESTMENTS
                        FLORIDA MUNICIPAL MONEY MARKET

NOVEMBER 30, 1997 (UNAUDITED)


Principal Amount                                                            Value
- --------------------------------------------------------------------------------------

                $2,000,000  Florida Housing Finance Agency
                                Rev., (Tiffany Club), VRDN,
                                4.00%, 12/3/97 (LOC:
                                NationsBank N.A.)                      $  2,000,000

                 2,200,000  Hillsborough County Aviation Auth.
                                Rev. Commercial Paper, 3.70%,
                                12/16/97 (LOC: National
                                Westminster Bank PLC)                     2,200,000

                 2,000,000  Indian River County Hospital
                                Commercial Paper, 3.70%,
                                12/16/97 (LOC: Kredietbank
                                N.V.)                                     2,000,000

                   950,000  Indian River County Industrial
                                Development Rev., (Florida
                                Convales), VRDN, 4.00%,
                                12/1/97 (LOC: Toronto
                                Dominion Bank)                              950,000

                 2,000,000  Jacksonville Electric Auth. Rev.,
                                Series 1997 B, 4.00%,
                                10/1/98                                   2,002,549

                   895,000  Jacksonville Health Facilities Auth.
                                Hospital Rev., Series 1997 A,
                                3.75%, 8/15/98 (MBIA)                       895,000

                 1,000,000  Lake County Sales Tax Rev.,
                                5.125%, 12/1/98 (FGIC)                    1,012,370

                   500,000  Marion County Housing Finance Auth.
                                Multi-Family Rev., (Summer Trace
                                Apartments), VRDN, 3.90%,
                                12/4/97 (LOC: Suntrust Bank,
                                Atlanta, GA)                                500,000

                   810,000  Martin County Industrial
                                Development Auth. Rev., (R.F.
                                Labs, Inc.), VRDN, 4.05%,
                                12/3/97 (LOC: Suntrust Bank
                                Central Florida, N.A.)                      810,000

                   300,000  Martin County Industrial
                                Development Auth. Rev., (Tampa
                                Farm Service, Inc.), VRDN, 4.05%,
                                12/3/97 (LOC: Suntrust Bank
                                Central Florida, N.A.)                      300,000

                   200,000  Ocean Highway and Port Auth.
                                Rev., (1993 Remarketing),
                                VRDN, 3.85%, 12/3/97
                                (LOC: ABN Amro Bank, N.A.)                  200,000

                 1,900,000  Ocean Highway and Port Auth.
                                Rev., (1995 Remarketing), VRDN,
                                3.85%, 12/3/97 (LOC: ABN
                                Amro Bank, N.A.)                          1,900,000


Principal Amount                                                            Value
- --------------------------------------------------------------------------------------

                $1,000,000  Orange County Health Facility Auth.
                                Rev., (Adventist Health System),
                                VRDN, 3.90%, 12/4/97 (LOC:
                                Rabobank)                              $  1,000,000

                 1,000,000  Pinellas County Industrial
                                Development Rev., (Better
                                Business Forms, Inc.), VRDN,
                                4.05%, 12/3/97 (LOC: Suntrust
                                Bank, Tampa Bay)                          1,000,000

                 2,100,000  Pinellas County Industrial Development Rev.,
                                (Hunter Douglas Project), VRDN, 4.05%, 12/3/97
                                (LOC: ABN Amro
                                Bank N.V.)                                2,100,000

                 1,960,000  Putnam County Development Auth.
                                Pollution Control Rev., (Seminole
                                Electric), 3.70%, 3/15/98
                                (National Rural Utilities
                                Cooperative Finance Corp.)                1,960,000

                 1,000,000  Sarasota County Utility System
                                Rev., Series 1996 A, 5.00%,
                                10/1/98 (FGIC)                            1,009,451

                   825,000  Volusia County Housing Finance
                                Auth. Multi-Family Housing Rev.,
                                Series 1985 H, (Sunpointe
                                Apartments), VRDN, 4.00%,
                                12/2/97 (LOC: Key Bank, N.A.)               825,000

                   700,000  Volusia County Industrial
                                Development Auth. Rev.,
                                (Daytona Plastix Inc.), VRDN,
                                4.05%, 12/3/97 (LOC: Suntrust
                                Bank Central Florida, N.A.)                 700,000
                                                                   ---------------------

TOTAL INVESTMENT SECURITIES -- 100.0%                                   $77,789,498
                                                                   =====================

</TABLE>

NOTES TO SCHEDULE OF INVESTMENTS

FGIC = Financial Guaranty Insurance Co.

GIC = Guaranteed Investment Contract

GO = General Obligation

LOC = Letter of Credit

MBIA = MBIA Insurance Company

SBBPA = Standby Bond Purchase Agreement

VRDN  = Variable Rate Demand Note.  Interest reset date is indicated and used in
      calculating  the  weighted  average  portfolio  maturity.  Rate  shown  is
      effective November 30, 1997.

See Notes to Financial Statements


8      FLORIDA MUNICIPAL MONEY MARKET         AMERICAN CENTURY INVESTMENTS


<TABLE>
<CAPTION>
                      FLORIDA INTERMEDIATE-TERM MUNICIPAL


                                       30-DAY                        30-DAY TAX-EQUIVALENT YIELDS
                                         SEC             28%              31%             36%              39.6%
                                        YIELD        Tax Bracket      Tax Bracket     Tax Bracket  Tax Bracket
- -----------------------------------------------------------------------------------------------------------------------
YIELDS AS OF NOVEMBER 30, 1997

<S>                                     <C>             <C>              <C>             <C>               <C>  
Florida Intermediate-Term Municipal     4.02%           5.58%            5.83%           6.28%             6.66%

                                                                                         AVERAGE ANNUAL RETURNS
                                                      6 MONTHS          1 YEAR          3 YEARS       LIFE OF
FUND(1)
- -----------------------------------------------------------------------------------------------------------------------
TOTAL RETURNS AS OF NOVEMBER 30, 1997(2)

Florida Intermediate-Term Municipal ..................  4.73%           6.78%           8.51%         6.85%

Lehman 5-Year General Obligation Index ...............  4.04%           5.38%           7.53%         6.25%(3)

Average Florida Intermediate
Municipal Debt Fund(4) ...............................  4.10%           5.28%           7.77%         6.01%(3)

Fund's Ranking Among Florida Intermediate
Municipal Debt Funds(4) ..............................   --          1 out of 20     3 out of 16     2 out of 13(3)
</TABLE>

(1)  Inception date was April 11, 1994.

(2)  Returns for periods less than one year are not annualized.

(3)  Returns from 4/30/94,  the date nearest the fund's inception for which data
     are available.

(4)  According to Lipper Analytical Services.

See pages 24-25 for more information about returns and Lipper fund rankings.

[mountain graph - data below]

GROWTH OF $10,000 OVER LIFE OF FUND

$10,000 investment made 4/30/94*

                         Value on 11/30/97
                 Florida
             Intermediate-Term         Lehman 5-Year
                Municipal                GO Index
                 $10,000                 $10,000
May-94           $10,093                 $10,056
Jun-94           $10,054                 $10,033
Jul-94           $10,195                 $10,142
Aug-94           $10,252                 $10,191
Sep-94           $10,173                 $10,114
Oct-94           $10,045                 $10,058
Nov-94           $9,876                  $9,993
Dec-94           $10,032                 $10,081
Jan-95           $10,212                 $10,178
Feb-95           $10,471                 $10,326
Mar-95           $10,539                 $10,490
Apr-95           $10,592                 $10,518
May-95           $10,830                 $10,749
Jun-95           $10,811                 $10,757
Jul-95           $10,930                 $10,908
Aug-95           $11,021                 $11,018
Sep-95           $11,069                 $11,051
Oct-95           $11,195                 $11,097
Nov-95           $11,297                 $11,192
Dec-95           $11,386                 $11,253
Jan-96           $11,513                 $11,387
Feb-96           $11,481                 $11,349
Mar-96           $11,328                 $11,288
Apr-96           $11,310                 $11,271
May-96           $11,300                 $11,258
Jun-96           $11,351                 $11,338
Jul-96           $11,477                 $11,413
Aug-96           $11,476                 $11,436
Sep-96           $11,552                 $11,522
Oct-96           $11,663                 $11,629
Nov-96           $11,819                 $11,791
Dec-96           $11,802                 $11,774
Jan-97           $11,837                 $11,805
Feb-97           $11,936                 $11,889
Mar-97           $11,820                 $11,755
Apr-97           $11,865                 $11,814
May-97           $12,049                 $11,942
Jun-97           $12,195                 $12,048
Jul-97           $12,448                 $12,266
Aug-97           $12,365                 $12,201
Sep-97           $12,504                 $12,310
Oct-97           $12,562                 $12,386
Nov-97           $12,619                 $12,425

Past  performance  does not  guarantee  future  results.  Investment  return and
principal  value will fluctuate,  and redemption  value may be more or less than
original cost.

The line representing the fund's total return includes  operating expenses (such
as transaction costs and management fees) that reduce returns, while the index's
total return line does not.  However,  the fund's  expenses were waived  through
December 31, 1995.  Had these fees not been  waived,  returns for those  periods
would have been lower.

* 4/30/94  is the  date  nearest  the  fund's  inception  for  which  comparable
  performance data exist. The fund's actual inception date is 4/11/94.


PORTFOLIO AT A GLANCE
                               11/30/97            5/31/97
Number of Securities              33                 34
Weighted Average Maturity      7.9 years          7.8 years
Average Duration               5.4 years          5.4 years
Expense Ratio                   0.57%*              0.65%

* Annualized.


SEMIANNUAL REPORT               FLORIDA INTERMEDIATE-TERM MUNICIPAL       9


                      FLORIDA INTERMEDIATE-TERM MUNICIPAL

MANAGEMENT Q & A

    An interview with Dave MacEwen and Ken Salinger,  portfolio  managers on the
Florida Municipal funds investment team.

HOW DID THE FUND PERFORM?

    The fund strongly outperformed both its Lipper peer group and its benchmark.
For the six months ended  November 30, 1997,  the fund's total return was 4.73%,
compared  with the 4.10% return of the average  Florida  intermediate  municipal
fund and the benchmark's 4.04% return.  According to Lipper Analytical Services,
the fund ranked #1 out of 20 "Florida Intermediate Municipal Funds" for the year
ended  November 30. (See the total  returns table on the previous page for other
fund performance comparisons.)

    The fund also provided  shareholders with  higher-than-average  yields.  The
fund's  30-day SEC yield as of  November 30 was 4.02%,  compared  with the 3.81%
yield of the average Florida intermediate fund.

WHY DID THE FUND PERFORM SO WELL?

    One  reason  was  our  conservative,  value-oriented  approach  to  security
selection--our credit research staff helped us find many undervalued  securities
that subsequently appreciated.

    Another reason the fund performed well was its below-average  expenses.  The
new  unified  fee  structure  shareholders  approved  in July 1997  lowered  the
management  fee for this fund to well below the  expense  ratio for the  average
Florida intermediate municipal fund. That directly benefits shareholders because
we're  delivering  the same strong  performance,  but at a lower cost. And other
things  being  equal,  lower  expenses  mean  higher  yields and returns for our
shareholders.

HOW WAS THE PORTFOLIO'S DURATION POSITIONED VERSUS THE FUND'S PEER GROUP?

    We kept the fund's  duration at around 5.5 years,  slightly longer than that
of its Lipper peer group  average,  which  helped  enhance  the fund's  returns.
(Duration  is a measure of a  portfolio's  sensitivity  to  changes in  interest
rates. The longer a fund's  duration,  the more its share price tends to rise or
fall when rates change.) When inflation remained benign and the possibility of a
short-term  interest  rate  increase  by  the  Federal  Reserve  evaporated,  we
lengthened  the  fund's  duration,  extending  it as far  as  5.75  years.  This
benefited performance because interest rates fell overall.

[bar graph - data below]

FLORIDA INTERMEDIATE-TERM MUNICIPAL'S
ONE-YEAR RETURNS SINCE INCEPTION (Periods ended November 30)

               Florida
           Intermediate-Term        Lehman 5-Year
              Municipal              GO Index
11/94*          -1.24%                -0.07%
11/95           14.39%                11.99%
11/96            4.61%                 5.36%
11/97            6.78%                 5.38%

This graph  illustrates the fund's returns since its inception and compares them
with the index's  returns.  The fund's expenses were waived through December 31,
1995. Had these fees not been waived,  returns for those periods would have been
less.  The fund's  total  returns  for the 1996 and 1997  fiscal  years  include
operating  expenses,  while the comparative  index's returns do not. See page 24
for a definition of the index.

Past  performance  is no  guarantee  of future  results.  Investment  return and
principal  value will fluctuate,  and redemption  value may be more or less than
original cost.

* Return from  4/30/94 (the date  nearest the fund's  inception  for which index
  data are available) to 11/30/94.


10      FLORIDA INTERMEDIATE-TERM MUNICIPAL    AMERICAN CENTURY INVESTMENTS


                      FLORIDA INTERMEDIATE-TERM MUNICIPAL

HOW DID YOU STRUCTURE THE FUND'S PORTFOLIO?

    We used a fairly bulleted structure as the period began, because we expected
the municipal yield curve to move from flat to steep.  (The yield curve steepens
when  long-term  interest  rates rise  faster  than  short-term  rates,  or when
short-term  rates fall faster than long-term  rates,  which happened  during the
summer.) To attain this bulleted  structure,  we chose more  intermediate  bonds
with six- to  seven-year  maturities,  which were  close to the  fund's  average
maturity.  As short-term interest rates fell during the summer, our intermediate
securities appreciated more than longer-term  securities,  which remained fairly
stable.

    However, as inflation stayed low,  longer-term  interest rates also began to
fall,  causing  the yield  curve to flatten  (long-term  rates fell  faster than
short-term  rates).  Responding to this shift in market sentiment,  we moved the
fund to a more  barbelled  position by switching  its  emphasis on  intermediate
securities to short and long  securities.  This change  allowed the fund to take
advantage  of  the  flattening  yield  curve  as  intermediate  municipals  were
outperformed by longer ones.  (When long-term  interest rates are falling,  long
bonds tend to produce  more price  appreciation  than  intermediate  securities,
while the fund's shorter securities provide a relatively steady yield.)

DID YOU CONTINUE USING SWAP TRADES TO ENHANCE THE FUND'S PERFORMANCE ?

    Yes, swaps played a significant  role. In a typical swap trade,  we exchange
one of the fund's  securities with a broker for one of their  securities that we
believe is  undervalued.  As mentioned in the previous  report,  we believe swap
trades are an excellent  way to add value to the fund.  These trades allow us to
take  advantage of occasional  market  inefficiencies  and to quickly adjust the
fund's structure.

    During  the third  quarter in  particular,  we made many  profitable  swaps,
partly  due to  unusually  high  levels of  municipal  issuance.  By the  fourth
quarter,  however,  the number of swaps decreased because new municipal issuance
began to dry up.

YOU  INCREASED THE  PERCENTAGE  OF  SECURITIES  RATED AAA IN THE FUND DURING THE
PERIOD, WHILE DECREASING THE AMOUNT OF SECURITIES RATED AA. WHY?

    We were able to  improve  the  fund's  credit  quality  significantly  while
sacrificing very little yield. That's because Florida's credit quality continued
to improve, and the difference in yield between AAA and AA securities decreased.
As a result,  we  tended to buy more AAA  securities,  but  didn't  give up much
yield.

[pie charts]

PORTFOLIO COMPOSITION BY SECURITY TYPE (as of 11/30/97)
Revenue Bonds            76%
Land-Secured             16%
GO                       7%
Prerefunded/ETM          1%


PORTFOLIO COMPOSITION BY SECURITY TYPE (as of 5/31/97)
Revenue Bonds            61%
Land-Secured             15%
GO                       13%
COPs/Leases              8%
Prerefunded/ETM          1%
Other                    2%


SEMIANNUAL REPORT               FLORIDA INTERMEDIATE-TERM MUNICIPAL       11


                      FLORIDA INTERMEDIATE-TERM MUNICIPAL

WHAT IS YOUR OUTLOOK FOR THE MUNICIPAL MARKET OVER THE NEXT SIX MONTHS?

    We have a positive  outlook.  Inflation  remains  tame,  having  risen at an
annualized  rate of only 1.8% for the first 11 months of 1997.  "Real"  interest
rates (nominal  interest rates minus the inflation  rate) are at relatively high
levels  that  should  inhibit   inflation  and  economic  growth  from  reaching
unmanageable  levels. In addition,  strong productivity gains should continue to
offset wage gains in the near future.

    Economic  turmoil in Asia also means a reduced  chance for  inflation in the
U.S. Slower growth overseas could take the edge off U.S. economic growth because
it means slower business for U.S.  exporters.  And a strong U.S. dollar and weak
Asian  currencies  mean  Americans will be able to buy imported goods at reduced
prices, putting price pressure on American products.

    The  shrinking  federal  budget  deficit also boosts the Treasury  market by
reducing the supply of available  Treasury  securities.  Higher  Treasury prices
help  make  municipal   securities  a  better  relative  value,  which  supports
municipals by attracting more buyers.

WITH THIS OUTLOOK IN MIND, WHAT ARE YOUR PLANS FOR THE FUND GOING FORWARD?

    For now,  we'll  likely keep the fund's  duration  neutral to slightly  long
compared with its Lipper peer group.

    We'll continue to work closely with our credit  research team as part of our
conservative,  value-oriented approach to security selection. We'll also keep an
eye out for  attractive  swap-trade  opportunities.  We will  also  continue  to
monitor the municipal yield curve closely,  looking for opportunities to enhance
returns by restructuring the fund to benefit from changing market conditions.

[pie charts]

PORTFOLIO COMPOSITION BY CREDIT RATING (as of 11/30/97)
AAA               81%
AA                19%


PORTFOLIO COMPOSITION BY CREDIT RATING (as of 5/31/97)
AAA               63%
AA                37%


12      FLORIDA INTERMEDIATE-TERM MUNICIPAL    AMERICAN CENTURY INVESTMENTS


<TABLE>
<CAPTION>
                            SCHEDULE OF INVESTMENTS
                      FLORIDA INTERMEDIATE-TERM MUNICIPAL

NOVEMBER 30, 1997 (UNAUDITED)


Principal Amount                                                            Value
- --------------------------------------------------------------------------------------

MUNICIPAL SECURITIES

<S>             <C>                                                   <C>
                $  300,000  Boca Raton Water and Sewer
                                Rev., 6.40%, 10/1/02                  $     312,258

                   300,000  Broward County School District
                                GO, 6.75%, 2/15/00(1)                       315,192

                 1,000,000  Dade County Aviation Rev., Series
                                1997 A, (Miami International
                                Airport), 5.50%, 10/1/02 (FSA)            1,047,660

                   500,000  Dade County Aviation Rev., Series
                                1995 E, 5.50%, 10/1/10
                                (AMBAC)                                     525,560

                 1,000,000  Dade County Housing Finance
                                Auth. Single-Family Mortgage
                                Rev., Series 1997 C, 4.05%,
                                10/16/98 (FGIC)                           1,000,080

                   500,000  Duval County School District GO,
                                6.25%, 8/1/05 (AMBAC)                       546,600

                   500,000  East County Water Control District
                                Rev., 5.375%, 11/1/01 (Asset
                                Guaranty)                                   519,295

                   300,000  Escambia County Housing Finance
                                Auth. Single-Family Mortgage
                                Rev., 6.00%, 4/1/02
                                (GNMA/FNMA)                                 310,314

                   350,000  Florida Housing Finance Agency
                                Multi-Family Housing Rev.,
                                5.35%, 6/1/00                               354,904

                   450,000  Florida Housing Finance Agency
                                Rev., (Williamsburg Village
                                Apartments), 5.60%, 12/1/07
                                (AMBAC)                                     471,780

                   500,000  Florida Housing Finance Agency
                                Rev., (Windwood), 5.65%,
                                12/1/07 (AXA Insurance)                     518,225

                   350,000  Gainesville Utilities System Rev.,
                                Series 1996 A, 5.75%, 10/1/09               384,395

                   800,000  Hillsborough County Aviation Auth.
                                Rev., Series 1997 A, (Tampa
                                International Airport), 5.00%,
                                10/1/05 (AMBAC)                             818,968

                   400,000  Hillsborough County Port District
                                Special Rev., 6.50%, 6/1/04
                                (FSA)                                       446,372


Principal Amount                                                            Value
- --------------------------------------------------------------------------------------

                $  400,000  Indian Trace Community
                                Development District Water
                                Management Special Benefit
                                Assessment, Series 1995 A,
                                5.25%, 5/1/03 (MBIA)                  $     418,592

                   750,000  Indian Trace Community
                                Development District Water
                                Management Special Benefit
                                Assessment, 5.00%, 5/1/10
                                (MBIA)                                      756,473

                   480,000  Jacksonville Electric Auth. Rev., (St.
                                John's River Power Project),
                                6.00%, 10/1/05                              529,766

                   500,000  Jacksonville Electric Auth. Rev.,
                                Series 1995 6-C, (St. John's
                                River Power Project), 6.50%,
                                10/1/01                                     539,160

                 1,250,000  Jacksonville Excise Tax Rev.,
                                5.20%, 10/1/04 (FGIC)                     1,295,487

                 1,000,000  Lee County Rev., Series 1997 A,
                                5.75%, 10/1/11 (MBIA)                     1,093,070

                 1,000,000  Miami Beach Parking Rev., 5.00%,
                                9/1/10 (FSA)                              1,007,380

                   550,000  Orange County Health Facilities
                                Auth. Rev., Series 1996 A,
                                6.00%, 10/1/04 (MBIA)                       602,828

                   450,000  Orlando and Orange County
                                Expressway Auth. Rev., 6.50%,
                                7/1/11 (FGIC)                               524,723

                   500,000  Orlando Utility Commission Water
                                and Electric Rev., 5.70%,
                                10/1/04                                     539,235

                   300,000  Pensacola Airport Rev., Series
                                1998 A, 6.00%, 10/1/01
                                (MBIA)(2)                                   314,235

                   500,000  Pensacola Airport Rev., Series
                                1997 B, 5.40%, 10/1/07
                                (MBIA)                                      527,695

                 1,000,000  Polk County Housing Finance
                                Auth. Multi-Family Housing Rev.,
                                Series 1997 A, (Winter Oaks
                                Apartments), 5.25%, 7/1/07
                                (FNMA)                                    1,025,670

                   200,000  Reedy Creek Improvement District
                                Utility Rev., Series 1991-1,
                                6.25%, 10/1/01, Prerefunded
                                at 101% of Par (MBIA)(3)                    216,356

See Notes to Financial Statements


SEMIANNUAL REPORT               FLORIDA INTERMEDIATE-TERM MUNICIPAL       13


                            SCHEDULE OF INVESTMENTS
                      FLORIDA INTERMEDIATE-TERM MUNICIPAL

NOVEMBER 30, 1997 (UNAUDITED)


Principal Amount                                                            Value
- --------------------------------------------------------------------------------------

                $1,675,000  Reedy Creek Improvement District
                                Utility Rev., Series 1, 5.50%,
                                10/1/05 (AMBAC)                        $  1,794,829

                   400,000  St. Cloud Utility Rev., 6.40%,
                                8/1/06 (MBIA)                               433,804

                   175,000  Tampa Palms Community
                                Development Special
                                Assessment Rev., 4.90%,
                                5/1/99 (MBIA)                               177,179

                 1,000,000  Tampa Sports Auth. Rev., 4.50%,
                                1/1/99 (MBIA)                             1,007,300

                   500,000  Volusia County School District GO,
                                6.20%, 8/1/03 (FGIC)                        539,780
                                                                   ---------------------

TOTAL INVESTMENT SECURITIES -- 100.0%                                   $20,915,165
                                                                   =====================
   (Cost $20,298,804)
</TABLE>


NOTES TO SCHEDULE OF INVESTMENTS

AMBAC = AMBAC Indemnity Corporation

FGIC = Financial Guaranty Insurance Co.

FNMA = Federal National Mortgage Association

FSA = Financial Security Assurance

GNMA = Government National Mortgage Association

GO = General Obligation

MBIA = MBIA Insurance Company

(1)  Denotes  security  which has been  segregated at the  custodian  bank for a
     when-issued security.

(2)  When-issued security.

(3)  Escrowed to maturity in U.S. Government securities.

See Notes to Financial Statements


14      FLORIDA INTERMEDIATE-TERM MUNICIPAL    AMERICAN CENTURY INVESTMENTS


                     STATEMENTS OF ASSETS AND LIABILITIES

                                          FLORIDA            FLORIDA
                                         MUNICIPAL       INTERMEDIATE-TERM
NOVEMBER 30, 1997 (UNAUDITED)           MONEY MARKET         MUNICIPAL

ASSETS

Investment securities, at value
  (amortized cost and identified
  cost of $20,298,804,
  respectively) (Note 3) ............... $77,789,498         $20,915,165

Cash ...................................   2,074,228           25,552

Investment in affiliated money
  market fund (Note 2) .................      --               502,834

Interest receivable ....................   598,961             294,478
                                       --------------      -------------
                                          80,462,687         21,738,029
                                       --------------      -------------
LIABILITIES

Disbursements in excess of
  demand deposit cash ..................    29,659             12,934

Payable for investments purchased ......      --              1,115,078

Payable for capital shares redeemed ....    7,615              12,163

Dividends payable ......................    17,156              5,335

Accrued management fees (Note 2) .......    42,812              8,457
                                       --------------      -------------
                                            97,242            1,153,967
                                       --------------      -------------
Net Assets ............................. $80,365,445         $20,584,062
                                       ==============      =============
CAPITAL SHARES

Outstanding (Unlimited number of
  shares authorized) ...................  80,365,445          1,942,597
                                       ==============      =============
Net Asset Value Per Share ..............    $1.00              $10.60
                                       ==============      =============
NET ASSETS CONSIST OF:

Capital paid in ........................ $80,365,445         $19,651,730

Accumulated undistributed net
  realized gain on investments .........      --               315,971

Net unrealized appreciation
  on investments (Note 3) ..............      --               616,361
                                       --------------      -------------
                                         $80,365,445         $20,584,062
                                       ==============      =============
See Notes to Financial Statements


SEMIANNUAL REPORT              STATEMENTS OF ASSETS AND LIABILITIES       15


                           STATEMENTS OF OPERATIONS

                                          FLORIDA            FLORIDA
FOR THE SIX MONTHS ENDED                  MUNICIPAL       INTERMEDIATE-TERM
NOVEMBER 30, 1997 (UNAUDITED)           MONEY MARKET         MUNICIPAL

INVESTMENT INCOME

Income:

Interest ...............................  $1,715,869         $   576,555
                                       --------------      -------------
Expenses (Note 2):

Investment advisory fees ...............   211,738             57,455

Administrative fees ....................    15,789              3,851

Printing and postage ...................    11,787              5,724

Transfer agency fees ...................    6,746               1,484

Auditing and legal fees ................    3,836                677

Custodian fees .........................    3,178               5,715

Trustees' fees and expenses ............    1,404               1,095

Organization costs .....................     219                 196

Other operating expenses ...............    2,272               1,947
                                       --------------      -------------
                                           256,969             78,144

Amount waived ..........................   (17,730)           (10,329)
                                       --------------      -------------
  Net expenses .........................   239,239             67,815
                                       --------------      -------------
Net investment income ..................  1,476,630            508,740
                                       --------------      -------------
REALIZED AND UNREALIZED
GAIN ON INVESTMENTS (NOTE 3)

Net realized gain on investments .......      --               264,519

Change in net unrealized
  appreciation on investments ..........      --               309,053
                                       --------------      -------------
Net realized and unrealized
gain on investments ....................      --               573,572
                                       --------------      -------------
Net Increase in Net Assets
Resulting from Operations ..............  $1,476,630         $1,082,312
                                       ==============      =============
See Notes to Financial Statements


16      STATEMENTS OF OPERATIONS               AMERICAN CENTURY INVESTMENTS

<TABLE>
<CAPTION>
                      STATEMENTS OF CHANGES IN NET ASSETS

SIX MONTHS ENDED NOVEMBER 30, 1997 (UNAUDITED) AND YEAR ENDED MAY 31, 1997

                                              FLORIDA MUNICIPAL                FLORIDA INTERMEDIATE-TERM
                                                 MONEY MARKET                           MUNICIPAL

Increase (Decrease) in Net Assets     November 30,          May 31,          November 30,         May 31,
                                          1997               1997                1997              1997
- -------------------------------------------------------------------------------------------------------------
OPERATIONS

<S>                                  <C>                <C>                <C>                <C>          
Net investment income ..........     $   1,476,630      $   4,590,342      $     508,740      $     512,380

Net realized gain on investments              --                 --              264,519             51,857

Change in net unrealized
  appreciation on investments ..              --                 --              309,053            177,601
                                     -------------      -------------      -------------      -------------
Net increase in net assets
   resulting from operations ...         1,476,630          4,590,342          1,082,312            741,838
                                     -------------      -------------      -------------      -------------
DISTRIBUTIONS TO
SHAREHOLDERS

From net investment income .....        (1,476,630)        (4,590,342)          (508,740)          (512,380)

From net realized gains on
  investment transactions ......              --                 --                 --              (39,475)
                                     -------------      -------------      -------------      -------------
Decrease in net assets
  from distributions ...........        (1,476,630)        (4,590,342)          (508,740)          (551,855)
                                     -------------      -------------      -------------      -------------
CAPITAL SHARE TRANSACTIONS

Proceeds from shares sold ......        49,163,958        211,673,148         10,823,384         14,609,503

Proceeds from reinvestment
  of distributions .............         1,380,332          4,249,244            437,614            409,403

Payments for shares redeemed ...       (82,308,046)      (203,786,255)        (7,763,123)        (9,015,107)
                                     -------------      -------------      -------------      -------------
Net increase (decrease) in net
  assets from capital share
  transactions .................       (31,763,756)        12,136,137          3,497,875          6,003,799
                                     -------------      -------------      -------------      -------------
Net increase (decrease) in
  net assets ...................       (31,763,756)        12,136,137          4,071,447          6,193,782

NET ASSETS

Beginning of period ............       112,129,201         99,993,064         16,512,615         10,318,833
                                     -------------      -------------      -------------      -------------
End of period ..................     $  80,365,445      $ 112,129,201      $  20,584,062      $  16,512,615
                                     =============      =============      =============      =============
TRANSACTIONS IN SHARES
OF THE FUNDS

Sold ...........................        49,163,958        211,673,148          1,040,203          1,420,596

Issued in reinvestment
  of distributions .............         1,380,332          4,249,244             41,498             39,811

Redeemed .......................       (82,308,046)      (203,786,255)          (736,772)          (876,033)
                                     -------------      -------------      -------------      -------------
Net increase (decrease) ........       (31,763,756)        12,136,137            344,929            584,374
                                     =============      =============      =============      =============
</TABLE>

See Notes to Financial Statements


SEMIANNUAL REPORT               STATEMENTS OF CHANGES IN NET ASSETS       17


                         NOTES TO FINANCIAL STATEMENTS

NOVEMBER 30, 1997 (UNAUDITED)

1. ORGANIZATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES

    ORGANIZATION--American  Century  Municipal  Trust (the Trust) is  registered
under the Investment  Company Act of 1940 as an open-end  management  investment
company.  American  Century - Benham Florida  Municipal Money Market Fund (Money
Market Fund) and American Century - Benham Florida  Intermediate-Term  Municipal
Fund  (Intermediate-Term  Fund) (the Funds) are two of the seven Funds issued by
the Trust.  The Funds are  non-diversified  under the 1940 Act. Their investment
objective  is to seek as high a level of  current  income  exempt  from  federal
income  taxes  as  is  consistent   with  prudent   investment   management  and
conservation of shareholders'  capital.  The Funds invest primarily in municipal
obligations with maturities based on each Fund's investment objective. The Funds
concentrate  their  investments  in a single state and  therefore  may have more
exposure  to credit  risk  related  to the state of  Florida  than a fund with a
broader  geographical  diversification.  The  following  significant  accounting
policies  relating  to the  Funds are in  accordance  with  accounting  policies
generally accepted in the investment company industry.

    SECURITY VALUATIONS--Portfolio  securities held by the Money Market Fund are
valued at amortized cost, which  approximates  current market value.  Securities
held by the Intermediate-Term Fund are valued through valuations obtained from a
commercial  pricing  service  or at the mean of the most  recent  bid and  asked
prices. When valuations are not readily available, securities are valued at fair
value as  determined  in  accordance  with  procedures  adopted  by the Board of
Trustees.

    SECURITY  TRANSACTIONS--Security  transactions are accounted for on the date
purchased  or  sold.  Net  realized  gains  and  losses  are  determined  on the
identified cost basis, which is also used for federal income tax purposes.

    INVESTMENT  INCOME--Interest  income is recorded  on the  accrual  basis and
includes accretion of discounts and amortization of premiums.

    INCOME TAX  STATUS--It is the Funds' policy to distribute all net investment
income and net realized capital gains to shareholders  and to otherwise  qualify
as a regulated  investment  company under the provisions of the Internal Revenue
Code. Accordingly, no provision has been made for federal or state taxes.

    DISTRIBUTIONS TO SHAREHOLDERS--Distributions  from net investment income for
the   Intermediate-Term   Fund  are  declared  daily  and  distributed  monthly.
Distributions  from  net  realized  gains  for the  Intermediate-Term  Fund  are
declared and paid  annually.  The Money  Market  Fund's  distributions  from net
investment income are declared and credited daily and distributed  monthly.  The
Money Market Fund does not expect to realize any long-term  capital  gains,  and
accordingly, does not expect to pay any capital gain distributions.

    The  character  of  distributions  made during the year from net  investment
income or net realized gains may differ from their ultimate characterization for
federal income tax purposes due to differences in the  recognition of income and
expense items for financial statement and tax purposes.

    FUTURES CONTRACTS--The Intermediate-Term Fund may buy and sell interest rate
futures  contracts  relating to debt  securities  and write and buy put and call
options  relating to interest rate futures  contracts.  The Fund may use futures
and options  transactions  to  maintain  cash  reserves  while  remaining  fully
invested,  to facilitate  trading,  to reduce  transaction  costs,  or to pursue
higher  investment  returns when a futures contract is priced more  attractively
than its underlying security or index. One of the risks of entering into futures
contracts may include the possibility  that the changes in value of the contract
may not correlate with the changes in value of the underlying  securities.  Upon
entering into a futures contract, the Fund is required to deposit either cash or
securities  in an amount equal to a certain  percentage  of the  contract  value
(initial margin).  Subsequent  payments  (variation margin) are made or received
daily,  in cash, by the Fund. The variation  margin is equal to the daily change
in the contract  value and is recorded as an unrealized  gain or loss.  The Fund
recognizes a realized gain or loss when the contract is closed or expires. There
were no open futures contracts at November 30, 1997.

    USE OF ESTIMATES--The preparation of financial statements in conformity with
generally accepted  accounting  principles requires management to make estimates
and assumptions  that affect the reported  amounts of assets and liabilities and
disclosure of  contingent  assets and  liabilities  at the date of the financial
statements  and the reported  amounts of increases  and  decreases in net assets
from  operations  during the  period.  Actual  results  could  differ from these
estimates.


18      NOTES TO FINANCIAL STATEMENTS          AMERICAN CENTURY INVESTMENTS


                         NOTES TO FINANCIAL STATEMENTS

NOVEMBER 30, 1997 (UNAUDITED)
- --------------------------------------------------------------------------------

2. TRANSACTIONS WITH RELATED PARTIES

    The  shareholders  of the Funds  approved a new  management  agreement  with
American Century Investment Management,  Inc. (ACIM) on July 30, 1997, effective
August 1, 1997,  which  replaced  the existing  contracts  between the Funds and
Benham Management  Corporation and American Century Services  Corporation (ACSC)
for advisory,  administrative and transfer agency services. Under the agreement,
ACIM will provide all services required by the Funds in exchange for one unified
management  fee.  Expenses  excluded from the agreement  are  brokerage,  taxes,
portfolio  insurance,  interest,  fees  and  expenses  of  Trustees  who are not
considered "interested persons" as defined in the Investment Company Act of 1940
(including  counsel fees) and extraordinary  expenses.  The annual rate at which
this fee is assessed is determined  monthly in a two-step process:  First, a fee
rate  schedule  is  applied  to the  assets  of all of the  funds in the  Fund's
investment  category which are managed by ACIM (the "Investment  Category Fee").
The  overall  investment  objective  of  each  Fund  determines  its  Investment
Category.  The three investment  categories are: the Money Market Fund Category,
the Bond Fund Category,  and the Equity Fund Category.  The Money Market Fund is
included in the Money  Market Fund  Category and the  Intermediate-Term  Fund is
included in the Bond Fund  Category.  Second,  a separate  fee rate  schedule is
applied to the assets of all of the funds managed by ACIM (the  "Complex  Fee").
The Investment  Category Fee and the Complex Fee are then added to determine the
unified  management  fee rate.  The  management fee is paid monthly by each Fund
based on each Fund's  aggregate  average  daily net assets  during the  previous
month multiplied by the monthly  management fee rate. The annualized  Investment
Category Fee schedule for each Fund is as follows:

    Money Market Fund:
      0.2700% of the first $1 billion
      0.2270% of the next $1 billion
      0.1860% of the next $3 billion
      0.1690% of the next $5 billion
      0.1580% of the next $15 billion
      0.1575% of the next $25 billion
      0.1570% of the average daily net assets over $50 billion


    Intermediate-Term Fund:
      0.2800% of the first $1 billion
      0.2280% of the next $1 billion
      0.1980% of the next $3 billion
      0.1780% of the next $5 billion
      0.1650% of the next $15 billion
      0.1630% of the next $25 billion
      0.1625% of the average daily net assets over $50 billion

    The annualized Complex Fee schedule (for all Funds) is as follows:

      0.3100% of the first $2.5 billion  
      0.3000% of the next $7.5 billion  
      0.2985% of the next $15 billion  
      0.2970% of the next $25 billion  
      0.2960% of the next $50 billion  
      0.2950% of the next $100 billion 
      0.2940% of the next $100 billion
      0.2930% of the next $200 billion 
      0.2920% of the next $250 billion 
      0.2910% of the next $500 billion 
      0.2900% of the average daily net assets over $1,250 billion

    Management  fees  of  $136,918  and  $40,258  were  incurred  under  the new
management  agreement  and  are  included  in  Investment  Advisory  Fees in the
Statements  of  Operations  for the Money Market Fund and the  Intermediate-Term
Fund, respectively. Expenses net of waiver, under the previous agreement for the
two months  ended July 31, 1997 were  $102,321  and $27,557 for the Money Market
Fund and the  Intermediate-Term  Fund,  respectively.  The  annualized  ratio of
operating  expenses to average net assets for the two months ended July 31, 1997
was 0.60% and 0.67% for the Money  Market Fund and the  Intermediate-Term  Fund,
respectively.

    Certain  officers  and  trustees  of the  Trust  are  also  officers  and/or
directors,  and,  as a  group,  controlling  stockholders  of  American  Century
Companies, Inc., the parent of the Trust's investment manager, ACIM, the Trust's
transfer  agent,  ACSC,  and  the  registered  broker  dealer  American  Century
Investment Services, Inc..

    As of November 30, 1997, the Intermediate-Term Fund had invested $502,834 in
shares of the Money Market Fund. The terms of the transaction  were identical to
those with  non-related  entities except that, to avoid  duplicative  management
fees, the  Intermediate-Term  Fund did not pay ACIM management fees with respect
to assets invested in the Money Market Fund.


SEMIANNUAL REPORT                     NOTES TO FINANCIAL STATEMENTS       19


                         NOTES TO FINANCIAL STATEMENTS

NOVEMBER 30, 1997 (UNAUDITED)
- --------------------------------------------------------------------------------
3. INVESTMENT TRANSACTIONS

    Purchases and sales of municipal debt obligations for the  Intermediate-Term
Fund,  excluding  short-term  investments,  totaled $24,507,875 and $22,137,082,
respectively.

    As of November 30, 1997,  accumulated  net unrealized  appreciation  for the
Intermediate-Term  Fund was  $616,361,  which  consisted  entirely of unrealized
appreciation.  The aggregate cost of investments for federal income tax purposes
for the Money  Market  Fund and the  Intermediate-Term  Fund was the same as the
cost for financial reporting purposes.


20      NOTES TO FINANCIAL STATEMENTS          AMERICAN CENTURY INVESTMENTS


<TABLE>
<CAPTION>
                             FINANCIAL HIGHLIGHTS
                        FLORIDA MUNICIPAL MONEY MARKET

    For a Share Outstanding Throughout the Years Ended May 31 (except as noted)

                                   1997(1)         1997            1996           1995          1994(2)
PER-SHARE DATA

Net Asset Value,
<S>                                 <C>            <C>             <C>            <C>            <C>  
Beginning of Period ..............  $1.00          $1.00           $1.00          $1.00          $1.00
                                 ----------     ----------      ----------     ----------     ----------
Income From
  Investment Operations

  Net Investment Income ..........  0.02           0.03            0.04           0.04            --
                                 ----------     ----------      ----------     ----------     ----------
Distributions

  From Net Investment Income ..... (0.02)         (0.03)          (0.04)         (0.04)           --
                                 ----------     ----------      ----------     ----------     ----------
Net Asset Value, End of Period ...  $1.00          $1.00           $1.00          $1.00          $1.00
                                 ==========     ==========      ==========     ==========     ==========
  Total Return(3) ................  1.66%          3.55%           3.86%          3.71%          0.40%

RATIOS/SUPPLEMENTAL DATA

Ratio of Operating Expenses
to Average Net Assets ............0.53%(4)         0.12%           0.01%           --             --

Ratio of Operating Expenses
to AverageNet Assets
(Before Expense Waiver) ..........0.57%(4)         0.66%           0.71%          0.88%        1.58%(4)

Ratio of Net Investment
Income to Average Net Assets .....3.29%(4)         3.48%           3.75%          3.93%        2.99%(4)

Ratio of Net Investment
Income to Average Net Assets
(Before Expense Waiver) ..........3.25%(4)         2.94%           3.05%          3.05%        1.41%(4)

Net Assets, End
of Period (in thousands) ......... $80,365       $112,129         $99,993        $45,147        $5,565
</TABLE>
- ----------

(1)  Six months ended November 30, 1997 (unaudited).

(2)  April 11, 1994 (inception) through May 31, 1994.

(3)  Total return assumes  reinvestment of dividends.  Total returns for periods
     less than one year are not annualized.

(4)  Annualized.

See Notes to Financial Statements


SEMIANNUAL REPORT                              FINANCIAL HIGHLIGHTS       21


<TABLE>
<CAPTION>
                             FINANCIAL HIGHLIGHTS
                      FLORIDA INTERMEDIATE-TERM MUNICIPAL

    For a Share Outstanding Throughout the Years Ended May 31 (except as noted)

                                        1997(1)         1997            1996           1995          1994(2)
PER-SHARE DATA

Net Asset Value,
<S>                                     <C>            <C>             <C>            <C>            <C>   
Beginning of Period ..................  $10.34         $10.18          $10.30         $10.11         $10.00
                                      ----------     ----------      ----------     ----------     ----------
Income From Investment Operations

  Net Investment Income ..............   0.23           0.46            0.52           0.52           0.07

  Net Realized and Unrealized
  Gain (Loss)
  on Investment Transactions .........   0.26           0.20           (0.08)          0.19           0.11
                                      ----------     ----------      ----------     ----------     ----------
  Total From Investment Operations ...   0.49           0.66            0.44           0.71           0.18
                                      ----------     ----------      ----------     ----------     ----------
Distributions

  From Net Investment Income .........  (0.23)         (0.46)          (0.52)         (0.52)         (0.07)

  From Net Realized Capital Gains ....    --           (0.04)          (0.04)           --             --
                                      ----------     ----------      ----------     ----------     ----------
  Total Distributions ................  (0.23)         (0.50)          (0.56)         (0.52)         (0.07)
                                      ----------     ----------      ----------     ----------     ----------
Net Asset Value, End of Period .......  $10.60         $10.34          $10.18         $10.30         $10.11
                                      ==========     ==========      ==========     ==========     ==========
  Total Return(3) ....................   4.73%          6.63%           4.34%          7.31%          1.79%

RATIOS/SUPPLEMENTAL DATA

Ratio of Operating Expenses
to Average Net Assets ................ 0.57%(4)         0.65%           0.13%           --             --

Ratio of Operating Expenses
to AverageNet Assets
(Before Expense Waiver) .............. 0.66%(4)         0.86%           0.88%          1.09%        1.92%(4)

Ratio of Net Investment
Income to Average Net Assets ......... 4.29%(4)         4.42%           5.05%          5.23%        5.02%(4)

Ratio of Net Investment Income
to Average Net Assets
(Before Expense Waiver) .............. 4.20%(4)         4.21%           4.30%          4.14%        3.10%(4)

Portfolio Turnover Rate ..............    98%            82%             66%            37%            6%

Net Assets, End
of Period (in thousands) .............  $20,584       $16,513          $10,319        $9,532         $5,892
</TABLE>
- ----------

(1)  Six months ended November 30, 1997 (unaudited).

(2)  April 11, 1994 (inception) through May 31, 1994.

(3)  Total  return   assumes   reinvestment   of  dividends  and  capital  gains
     distributions, if any. Total returns for periods less than one year are not
     annualized.

(4)  Annualized.

See Notes to Financial Statements


22      FINANCIAL HIGHLIGHTS                   AMERICAN CENTURY INVESTMENTS


                             PROXY VOTING RESULTS

    An annual meeting of shareholders  was held on July 30, 1997, to vote on the
following  proposals.  All of the  proposals  received the required  majority of
votes and were adopted.

    A summary of voting results is listed below each proposal.

PROPOSAL 1:

    To vote on the  selection  by the Board of Trustees of Coopers & Lybrand LLP
as independent auditors for the Trust.

                          MUNICIPAL          INTERMEDIATE-
                        MONEY MARKET         TERM MUNICIPAL

    For:                 62,589,478             1,026,612
    Against:             2,066,291               25,426
    Abstain:              580,265                 2,974


PROPOSAL 2:

    To vote on the  approval of a Management  Agreement  with  American  Century
Investment Management, Inc.

                          MUNICIPAL           INTERMEDIATE-
                        MONEY MARKET         TERM MUNICIPAL

    For:                 60,994,259              998,927
    Against:             3,521,917               42,416
    Abstain:              719,858                13,669


PROPOSAL 3:

    To vote on the  adoption  of  standardized  investment  limitations  for the
following items:

*  Amend the fundamental investment limitation concerning borrowing.

                          MUNICIPAL          INTERMEDIATE-
                        MONEY MARKET         TERM MUNICIPAL

    For:                 57,526,258              936,381
    Against:             6,829,959               89,880
    Abstain:              877,451                 6,770
    Broker
      Non-Vote:             2,366                21,981

*  Amend the fundamental investment limitation concerning lending.

                          MUNICIPAL           INTERMEDIATE-
                        MONEY MARKET         TERM MUNICIPAL

    For:                 58,616,129              936,381
    Against:             5,740,088               89,880
    Abstain:              877,451                 6,770
    Broker
      Non-Vote              2,366                21,981

*  Amend the fundamental investment limitation concerning underwriting.

                          MUNICIPAL          INTERMEDIATE-
                        MONEY MARKET         TERM MUNICIPAL

    For:                 58,616,129              936,381
    Against:             5,740,088               89,880
    Abstain:              877,451                 6,770
    Broker
      Non-Vote:             2,366                21,981

*  Amend the fundamental investment limitation concerning commodities.

                          MUNICIPAL           INTERMEDIATE-
                        MONEY MARKET         TERM MUNICIPAL

    For:                 58,506,138              931,282
    Against:             5,850,079               90,678
    Abstain:              877,451                11,071
    Broker
      Non-Vote:             2,366                21,981

*  Eliminate the fundamental  investment  limitation  concerning  investments in
   oil, gas and mineral exploration development programs.

                          MUNICIPAL           INTERMEDIATE-
                        MONEY MARKET         TERM MUNICIPAL

    For:                 58,605,974              932,080
    Against:             5,750,243               89,880
    Abstain:              877,451                11,071
    Broker
      Non-Vote:             2,366                21,981


SEMIANNUAL REPORT                              PROXY VOTING RESULTS       23


                            BACKGROUND INFORMATION

INVESTMENT PHILOSOPHY & POLICIES

    The Benham Group  offers 38  fixed-income  funds,  ranging from money market
funds to long-term bond funds and including  both taxable and tax-exempt  funds.
Each fund is  managed  to  provide  a "pure  play" on a  specific  sector of the
fixed-income market. To ensure adherence to this principle,  the basic structure
of each fund's  portfolio  is tied to a specific  market  index.  Fund  managers
attempt  to add  value by making  modest  portfolio  adjustments  based on their
analysis of  prevailing  market  conditions.  Investment  decisions  are made by
management teams, which meet regularly to discuss market analysis and investment
strategies.

    In addition to these principles, each fund has its own investment policies:

    The FLORIDA  MUNICIPAL  FUNDS seek to provide  interest  income  exempt from
federal  income  taxes by  investing at least 65% of their net assets in Florida
municipal  securities.  Fund  shares are  intended to be exempt from the Florida
intangibles tax.

    Depending  on your tax  status,  investment  income  may be  subject  to the
federal  alternative  minimum  tax.  Capital  gains are not exempt from  federal
income tax.

    FLORIDA  MUNICIPAL  MONEY MARKET is a money market fund that seeks  interest
income exempt from federal income taxes by investing  primarily in high-quality,
short-term Florida municipal securities.

    Investments  in Florida  Municipal  Money  Market are  neither  insured  nor
guaranteed by the U.S.  government.  Yields will fluctuate,  and there can be no
assurance  that the fund will be able to maintain a stable net asset value of $1
per share.

    FLORIDA  INTERMEDIATE-TERM  MUNICIPAL  is a  variable-price  bond  fund that
invests  primarily  in  intermediate-term   Florida  municipal  securities  with
maturities of four or more years. The fund maintains a weighted average maturity
of 5-10 years.

COMPARATIVE INDICES

    The index listed  below is used in the report to serve as a  comparison  for
the  performance  of a  fund.  It is not an  investment  product  available  for
purchase.

    The LEHMAN 5-YEAR  MUNICIPAL  GENERAL  OBLIGATION  INDEX is a municipal bond
index  composed of more than 11,000 bonds with  maturities of four to six years.
The bonds are rated BBB or higher by Standard & Poor's,  with an average  rating
of AA. The average maturity of the index is five years.

LIPPER RANKINGS

    LIPPER  ANALYTICAL  SERVICES,  INC. is an  independent  mutual fund  ranking
service.  Rankings are based on average  annual returns for each fund in a given
category for the periods  indicated.  Rankings are not included for periods less
than one year.

    The Lipper categories for the Florida Municipal funds are:

    OTHER STATES TAX-EXEMPT MONEY MARKET FUNDS (Florida  Municipal Money Market)
- --funds that invest in high-quality  municipal  obligations with dollar-weighted
average maturities of less than 90 days.

    FLORIDA  INTERMEDIATE   MUNICIPAL  DEBT  FUNDS  (Florida   Intermediate-Term
Municipal)--funds  that invest at least 65% of their  assets in  municipal  debt
issues that are exempt from taxation in Florida,  with  dollar-weighted  average
maturities of 5-10 years.

INVESTMENT TEAM LEADERS

  Portfolio Managers           Bryan Karcher
                               Dave MacEwen
                               Ken Salinger

  Credit Research Manager      Steven Permut


24      BACKGROUND INFORMATION                 AMERICAN CENTURY INVESTMENTS


                                   GLOSSARY

RETURNS

* TOTAL  RETURN  figures  show the overall  percentage  change in the value of a
hypothetical  investment  in  the  fund  and  assume  that  all  of  the  fund's
distributions are reinvested.

* AVERAGE ANNUAL RETURNS  illustrate the annually  compounded returns that would
have produced the fund's cumulative total returns if the fund's  performance had
been  constant  over the  entire  period.  Average  annual  returns  smooth  out
variations  in a fund's  return;  they are not the same as  fiscal  year-by-year
results.  For  fiscal  year-by-year  returns,  please  refer  to the  "Financial
Highlights" on pages 21-22.

YIELDS

* 7-DAY  CURRENT  YIELD  is  calculated  based  on the  income  generated  by an
investment  in the fund over a seven-day  period and is  expressed  as an annual
percentage rate.

* 7-DAY  EFFECTIVE  YIELD is  calculated  similarly,  although  this  figure  is
slightly  higher than the fund's 7-Day  Current  Yield because of the effects of
compounding.  The 7-Day  Effective  Yield  assumes  that income  earned from the
fund's investments is reinvested and generating additional income.

* 30-DAY SEC YIELD  represents net  investment  income earned by the fund over a
30-day period,  expressed as an annualized  percentage  rate based on the fund's
share price at the end of the 30-day period. The SEC yield should be regarded as
an estimate  of the fund's  investment  income,  and it may not equal the fund's
actual income distribution rate, the income paid to a shareholder's  account, or
the income reported in the fund's financial statements.

*  TAX-EQUIVALENT  YIELDS show the taxable  yields that  investors  in a federal
income tax bracket would have to earn before taxes to equal the fund's  tax-free
yield.

INVESTMENT TERMS

* BASIS POINT--a basis point equals one  one-hundredth of a percentage point (or
0.01%). Therefore, 100 basis points equals one percentage point (or 1%).

* YIELD CURVE--a graphic representation of the relationship between maturity and
yield  for  fixed-income   securities.   Yield  curve  graphs  plot  lengthening
maturities along the horizontal axis and rising yields along the vertical axis.

PORTFOLIO STATISTICS

* NUMBER OF SECURITIES--the  number of different  securities held by a fund on a
given date.

*  WEIGHTED  AVERAGE  MATURITY  (WAM)--a  measurement  of the  sensitivity  of a
fixed-income  portfolio to interest rate changes. WAM indicates the average time
until the securities in the portfolio mature, weighted by dollar amount.

*  AVERAGE  DURATION--another  measure  of  the  sensitivity  of a  fixed-income
portfolio to interest rate changes.  Duration is a time-weighted  average of the
interest and principal payments of the securities in a portfolio.

* EXPENSE RATIO--the  operating expenses of the fund,  expressed as a percentage
of average net assets.  Shareholders pay an annual fee to the investment manager
for  investment  advisory  and  management  services.  The expenses and fees are
deducted from fund income, not from each shareholder account. (See Note 2 in the
Notes to Financial Statements.)

TYPES OF MUNICIPAL SECURITIES

*  COPS/LEASES--securities  issued to finance public property improvements (such
as city halls and police  stations) and  equipment  purchases.  Certificates  of
participation  represent long-term debt obligations,  while leases have a higher
risk profile than GOs because they require annual appropriation.

* GO  BONDS--general  obligation  securities  backed by the taxing  power of the
issuer.

*  LAND-SECURED  BONDS--securities  such as Mello-Roos  bonds and 1915-Act bonds
that are issued to finance real estate development projects.

* PREREFUNDED BONDS/ETM BONDS--securities  refinanced or escrowed to maturity by
the issuer because of their premium coupons (higher-than-market interest rates).
These  bonds  tend to have  higher  credit  ratings  because  they are backed by
Treasury securities.

*  REVENUE  BONDS--securities  backed by  revenues  from  sales  taxes or from a
specific  project,  system or facility (such as a hospital,  electric utility or
water system).


SEMIANNUAL REPORT                                          GLOSSARY       25

[american century logo]
American
Century(reg.sm)

P.O. BOX 419200
KANSAS CITY, MISSOURI
64141-6200

INVESTOR SERVICES:
1-800-345-2021 OR 816-531-5575

AUTOMATED INFORMATION LINE:
1-800-345-8765

TELECOMMUNICATIONS DEVICE FOR THE DEAF:
1-800-634-4113 OR 816-444-3485

FAX: 816-340-7962

INTERNET: WWW.AMERICANCENTURY.COM


AMERICAN CENTURY MUNICIPAL TRUST


INVESTMENT MANAGER

AMERICAN CENTURY INVESTMENT MANAGEMENT, INC.

KANSAS CITY, MISSOURI


THIS  REPORT AND THE  STATEMENTS  IT  CONTAINS  ARE  SUBMITTED  FOR THE  GENERAL
INFORMATION OF OUR  SHAREHOLDERS.  THE REPORT IS NOT AUTHORIZED FOR DISTRIBUTION
TO  PROSPECTIVE  INVESTORS  UNLESS  PRECEDED  OR  ACCOMPANIED  BY  AN  EFFECTIVE
PROSPECTUS.


(c) 1998 AMERICAN CENTURY SERVICES CORPORATION FUNDS DISTRIBUTOR, INC.


9801           [recycled logo]
SH-BKT-10687      Recycled
<PAGE>
                                  SEMIANNUAL
                                    REPORT

                            [american century logo]
                                    American
                                Century(reg.sm)

                               NOVEMBER 30, 1997

                                    BENHAM
                                     GROUP

                      Arizona Intermediate-Term Municipal

                               TABLE OF CONTENTS

Report Highlights .......................................................      1
Our Message to You ......................................................      2
Market Perspective ......................................................      3
Performance & Portfolio Information .....................................      4
Management Q & A ........................................................      5
Schedule of Investments .................................................      8
Statement of Assets and Liabilities .....................................     10
Statement of Operations .................................................     11
Statements of Changes in Net Assets .....................................     12
Notes to Financial Statements ...........................................     13
Financial Highlights ....................................................     15
Proxy Voting Results ....................................................     16
Background Information
           Investment Philosophy & Policies .............................     20
           Comparative Indices ..........................................     20
           Lipper Rankings ..............................................     20
           Investment Team Leaders ......................................     20
Glossary ................................................................     21

       American Century  Investments  offers you nearly 70 fund choices covering
stocks,  bonds,  money markets,  specialty  investments and blended  portfolios.
We've organized our funds into three distinct groups,  based on investment style
and objectives, to help simplify your fund decisions. These groups appear below.


                  AMERICAN CENTURY INVESTMENTS--FAMILY OF FUNDS
- -------------------------------------------------------------------------------
        Benham                American Century       Twentieth Century(reg. tm)
     Group(reg. tm)                 Group                      Group
- -------------------------------------------------------------------------------
   MONEY MARKET FUNDS         ASSET ALLOCATION &           GROWTH FUNDS
 GOVERNMENT BOND FUNDS          BALANCED FUNDS          INTERNATIONAL FUNDS
 DIVERSIFIED BOND FUNDS   CONSERVATIVE EQUITY FUNDS
  MUNICIPAL BOND FUNDS         SPECIALTY FUNDS
- -------------------------------------------------------------------------------
      Arizona
  Intermediate-Term
     Municipal

We welcome your comments or questions about this report.  
See the back cover for ways to contact us by mail, phone or e-mail.

Twentieth  Century and American Century are registered marks of American Century
Services  Corporation.  Benham Group is a registered  mark of Benham  Management
Corporation.


                         AMERICAN CENTURY INVESTMENTS

                               REPORT HIGHLIGHTS

MARKET PERSPECTIVE

*   Municipal  securities  produced  solid  returns  during the six months ended
    November 30, 1997.

*   Despite lower yields overall,  low  unemployment and inflation fears sparked
    bond market volatility.

*   Credit spreads fell to historically  low levels because of improving  credit
    quality and the increase in the number of municipal  securities insured with
    a AAA rating.

MUNICIPAL CREDIT REVIEW

*   Arizona continued to be one of the fastest-growing  states during the second
    half of 1997.

*   While the state's population rose, its overall  unemployment rate fell to 5%
    by August.

*   Job growth was most impressive in the Phoenix and Tucson areas.

*   A steady increase in taxable sales improved the state's budget, which led to
    improvement in overall municipal credit quality.

MANAGEMENT Q & A

*   The fund's  six-month  return was  slightly  above the return of the average
    intermediate municipal fund and matched the return of its benchmark.

*   We  maintained a slightly  longer  duration than the fund's peers because of
    our expectations for lower interest rates.

*   While we continue actively searching for bargains among lower-rated  issues,
    the mainstay of the fund continues to be municipal  securities rated AAA and
    AA.

*   Going  forward,  we'll likely keep the fund's  duration  neutral to slightly
    long compared with the average of its peers.


     ARIZONA INTERMEDIATE-TERM MUNICIPAL

TOTAL RETURNS:              AS OF 11/30/97
      6 Months                      4.04%*
      1 Year                          5.02%

30-DAY SEC YIELD:                     4.01%

NET ASSETS:                  $36.0 million
      (AS OF 11/30/97)

INCEPTION DATE:                     4/11/94

TICKER SYMBOL:                        BEAMX

* Not annualized.

Many of the investment  terms in this report are defined in the Glossary on page
21.


SEMIANNUAL REPORT                                 REPORT HIGHLIGHTS       1


                              OUR MESSAGE TO YOU

              [photo of James E. Stowers III and James M. Benham]

    The Benham  Arizona  Intermediate-Term  Municipal fund performed well during
the  six  months   ended   November   30,   1997,   rewarding   investors   with
better-than-average returns. Healthy economic growth in Arizona coupled with low
inflation  provided a favorable  backdrop for strong municipal bond performance.
Our municipal  investment  team provides  details on market  conditions and your
fund's performance on the following pages.

    On the  corporate  front,  the latter half of 1997  proved as  eventful  for
American  Century as it was for  investors.  In July,  J.P.  Morgan & Co.,  Inc.
agreed to become a significant minority shareholder in our company. Through this
business  partnership,  we  see  many  opportunities  to  expand  the  range  of
investment  choices and services we offer you. J.P.  Morgan has been in business
for more than 150 years, serving institutions,  governments and individuals with
complex  financial needs.  Within the framework of this  relationship,  American
Century  will  continue  to operate as an  independent  company.  Our  corporate
management  team will remain the same, and the Stowers family will retain voting
control of the company.

    On a more  personal  note,  1997 was the year we said  farewell  to James M.
Benham,  founder of the Benham Group of mutual funds. Mr. Benham,  who announced
his  retirement in December,  was a pioneer in the no-load  mutual fund industry
and the father of Capital  Preservation  Fund,  the first money  market fund for
individual  investors.  With the  integration  of Benham and  Twentieth  Century
successfully  completed,  Mr.  Benham  felt it was  time to step  back  from the
business and enjoy a well-earned retirement,  confident that he leaves the funds
he founded in very  capable  hands.  Though his  counsel  and  guidance  will be
missed,  much of the  Benham  culture  has  become a part of  American  Century,
including the educational  investor seminar program Mr. Benham created.  And two
of his sons,  Jim A. Benham and Tim Benham,  remain with the company to carry on
the Benham tradition.

    Looking  forward,  1998 will be a  landmark  year for us,  marking  the 40th
anniversary of the introduction of our first two funds, Twentieth Century Growth
and  Twentieth  Century  Select.  Not many fund  companies  have a 40-year track
record, nor have many built a fund family such as ours, which includes nearly 70
stock,  bond, money market and combination  funds that provide  investors with a
wide range of choice and flexibility.

    Whatever your financial  goals, we believe we have an outstanding  lineup of
funds to help you reach them.

    Sincerely,

/s/James E. Stowers III                  /s/James M. Benham
James E. Stowers III                     James M. Benham
Chief Executive Officer                  Vice Chairman
American Century Investment              American Century Investment
   Management, Inc.                         Management, Inc


2      OUR MESSAGE TO YOU                     AMERICAN CENTURY INVESTMENTS


                              MARKET PERSPECTIVE

[line graph - data below]

MUNICIPAL YIELD CURVES

Years to Maturity          11/30/97               5/31/97
1                           3.690%                3.850%
2                           3.840%                4.150%
3                           3.960%                4.350%
4                           4.070%                4.500%
5                           4.170%                4.600%
6                           4.260%                4.660%
7                           4.350%                4.720%
8                           4.430%                4.780%
9                           4.510%                4.840%
10                          4.590%                4.900%
11                          4.666%                4.976%
12                          4.742%                5.052%
13                          4.818%                5.128%
14                          4.894%                5.204%
15                          4.970%                5.280%
16                          5.000%                5.308%
17                          5.030%                5.336%
18                          5.060%                5.364%
19                          5.090%                5.392%
20                          5.120%                5.420%
21                          5.126%                5.426%
22                          5.132%                5.432%
23                          5.138%                5.438%
24                          5.144%                5.444%
25                          5.150%                5.450%
26                          5.154%                5.454%
27                          5.158%                5.458%
28                          5.162%                5.462%
29                          5.166%                5.466%
30                          5.170%                5.470%

Source: Bloomberg Financial Markets%


SOLID MUNICIPAL BOND RETURNS

    Municipal  securities  produced  solid  returns  during the six months ended
November 30, 1997. As the accompanying  graph indicates,  yields fell across the
maturity spectrum.

    For the period, the Lehman Brothers Long-Term  Municipal Bond Index returned
6.90%.  Intermediate-term securities,  represented by the Lehman Brothers 5-Year
Municipal General Obligation Index, returned 4.04%. The short-term Merrill Lynch
0- to 3-Year Municipal Index posted a 2.62% return.

INCREASED MARKET VOLATILITY

    Despite lower interest rates overall, municipal yields fluctuated throughout
the period.  Uncertainty  in the bond market over how long  inflation can remain
tame with the  unemployment  rate so low was  largely  responsible  for the rate
fluctuations.  Low  unemployment  has  led  to  inflation  in the  past  because
companies tend to raise wages in an attempt to keep or hire  employees.  Because
wages  account for about  two-thirds of all business  costs,  higher wages often
lead to rising prices.

    But despite a November  1997  unemployment  rate of  4.6%--the  lowest in 24
years--and signs of rising wages, overall inflation remained low. Inflation,  as
measured by the  government's  consumer price index,  was just 1.9% for the year
ended November 30, 1997.

    Increased  productivity  was a key reason wages could rise without  sparking
inflation,  as businesses  reaped the rewards of huge  investments in technology
and other productivity  tools.  According to the Labor Department,  productivity
gains in the third quarter of 1997 were the fastest in five years.

    Turmoil in Asian  financial  markets also  contributed  to volatility in the
U.S. bond market. A currency crisis in Southeast Asia caused investors to seek a
"safe-haven"  in  U.S.  Treasury   securities.   Because  demand  for  municipal
securities  is  often  predicated  on the  relative  prices  of  municipals  and
Treasurys,  big swings in the  Treasury  market can carry over to the  municipal
market.

IMPACT OF BOND INSURANCE

    An  increase  in the  amount  of  debt  being  issued  with  bond  insurance
contributed to a narrower  spread,  or difference in yield,  between AAA and BBB
securities.

    About  60% of all  municipal  debt now comes to  market  insured  with a AAA
rating.  That has boosted credit quality generally by dramatically  reducing the
amount of debt issued at the lower investment  grades. But it has also increased
demand for a shrinking supply of lower-rated,  higher-yielding  securities.  The
net effect has been to push credit spreads to historically low levels.


SEMIANNUAL REPORT                                MARKET PERSPECTIVE       3


<TABLE>
<CAPTION>
                      PERFORMANCE & PORTFOLIO INFORMATION

                                          30-DAY                        30-DAY TAX-EQUIVALENT YIELDS
                                            SEC           31.02%           33.90%          34.59%            39.33%
                                           YIELD        Tax Bracket      Tax Bracket     Tax Bracket  Tax Bracket
- ---------------------------------------------------------------------------------------------------------------------------
YIELDS AS OF NOVEMBER 30, 1997

<S>                                        <C>             <C>              <C>             <C>               <C>  
Arizona Intermediate-Term Municipal        4.01%           5.81%            6.07%           6.13%             6.61%

                                                                                              AVERAGE ANNUAL RETURNS
                                                         6 MONTHS          1 YEAR           3 YEARS      LIFE OF
FUND(1)
- ---------------------------------------------------------------------------------------------------------------------------
TOTAL RETURNS AS OF NOVEMBER 30, 1997(2)

Arizona Intermediate-Term Municipal .....................  4.04%            5.02%            7.81%        6.63%

Lehman 5-Year General Obligation Index ..................  4.04%            5.38%            7.53%     6.25%(3)

Average Other States Intermediate
Municipal Debt Fund(4) ..................................  3.96%            5.21%            7.74%     5.87%(3)

Fund's Ranking Among Other States
Intermediate Municipal Debt Funds(4) ....................   --          44 out of 74     36 out of 63     6 out of 54(3)
</TABLE>

Yields are defined in the Glossary on page 21.

(1) Inception date was April 11, 1994.

(2) Returns for periods less than one year are not annualized.

(3) Returns from 4/30/94,  the date nearest the fund's  inception for which data
    are available.

(4) According to Lipper Analytical Services.

See pages 20-21 for more information  about returns,  the comparative  index and
Lipper fund rankings.

[mountain graph - data below]

GROWTH OF $10,000 OVER LIFE OF FUND
$10,000 investment made 4/30/94*

                               Value on 11/30/97
                      Arizona
                  Intermediate-Term        Lehman 5-Year
                     Municipal                GO Index
                      $10,000                 $10,000
May-94                $10,092                 $10,056
Jun-94                $10,064                 $10,033
Jul-94                $10,234                 $10,142
Aug-94                $10,280                 $10,191
Sep-94                $10,202                 $10,114
Oct-94                $10,083                 $10,058
Nov-94                $9,973                  $9,993
Dec-94                $10,098                 $10,081
Jan-95                $10,268                 $10,178
Feb-95                $10,443                 $10,326
Mar-95                $10,562                 $10,490
Apr-95                $10,625                 $10,518
May-95                $10,852                 $10,749
Jun-95                $10,855                 $10,757
Jul-95                $10,985                 $10,908
Aug-95                $11,085                 $11,018
Sep-95                $11,130                 $11,051
Oct-95                $11,233                 $11,097
Nov-95                $11,343                 $11,192
Dec-95                $11,426                 $11,253
Jan-96                $11,574                 $11,387
Feb-96                $11,541                 $11,349
Mar-96                $11,365                 $11,288
Apr-96                $11,378                 $11,271
May-96                $11,357                 $11,258
Jun-96                $11,428                 $11,338
Jul-96                $11,540                 $11,413
Aug-96                $11,539                 $11,436
Sep-96                $11,614                 $11,522
Oct-96                $11,724                 $11,629
Nov-96                $11,900                 $11,791
Dec-96                $11,853                 $11,774
Jan-97                $11,874                 $11,805
Feb-97                $11,948                 $11,889
Mar-97                $11,809                 $11,755
Apr-97                $11,852                 $11,814
May-97                $12,010                 $11,942
Jun-97                $12,122                 $12,048
Jul-97                $12,386                 $12,266
Aug-97                $12,270                 $12,201
Sep-97                $12,407                 $12,310
Oct-97                $12,453                 $12,386
Nov-97                $12,498                 $12,425

Past  performance  does not  guarantee  future  results.  Investment  return and
principal  value will fluctuate,  and redemption  value may be more or less than
original cost.

The line representing the fund's total return includes  operating expenses (such
as transaction costs and management fees) that reduce returns, while the index's
total return line does not.  However,  the fund's  expenses were waived  through
December  31,  1995.  Had these fees not been  waived,  returns  would have been
lower.

*  4/30/94  is the date  nearest  the  fund's  inception  for  which  comparable
performance data exist. The fund's actual inception date is 4/11/94.


PORTFOLIO AT A GLANCE
                               11/30/97            5/31/97
Number of Securities              39                 37
Weighted Average Maturity      7.5 years          7.2 years
Average Duration               5.3 years          5.0 years
Expense Ratio                   0.57%*              0.66%

* Annualized.


4      PERFORMANCE & PORTFOLIO INFORMATION    AMERICAN CENTURY INVESTMENTS


                                MANAGEMENT Q&A

    An  interview  with  Colleen  Denzler,  a  portfolio  manager on the Arizona
Intermediate-Term Municipal fund investment team.

HOW DID THE FUND PERFORM?

    The fund benefited from falling  interest rates and outperformed the average
intermediate  municipal  debt fund.  For the six months ended November 30, 1997,
the fund's total return was 4.04%, compared with the 3.96% average return of the
83 "Other States Intermediate Municipal Debt Funds" tracked by Lipper Analytical
Services. The fund's return also matched the 4.04% return of its benchmark,  the
Lehman  5-Year  General  Obligation  Index.  (See the Total Returns table on the
previous page for other fund performance comparisons.)

HOW DID YOU MANAGE THE FUND'S DURATION DURING THE PERIOD?

    A lack of inflation and falling interest rates led us to maintain a slightly
longer-than-neutral   duration.   (Duration  is  a  measure  of  a   portfolio's
sensitivity to changes in interest rates. The longer a fund's duration, the more
its share price tends to rise or fall when rates  change.)  The fund's  duration
began the period at around five years.  We extended to around 5.5 years during a
sharp rally in July and August,  making the fund's duration slightly longer than
that of the average intermediate municipal debt fund.

    Shortly thereafter, we moved the fund to a more neutral 5.25 years. Although
we maintained this duration during October, when the market briefly declined, it
was slightly long compared with its peers because many of them  shortened  their
durations.  The fund's relatively long position proved beneficial as bond prices
rose in late October and November.

WHAT MARKET FACTORS HAD AN IMPACT ON THE FUND?

    One of the most  important  factors we  monitored  during the period was the
potential  shortening of the fund's  duration caused by bonds "trading to call."
Many municipal securities are issued with call provisions,  which means they can
be  paid  off  by  the  issuer  before  maturity.   When  interest  rates  fall,
municipalities  often  find it  financially  rewarding  to  refinance  the bonds
they've issued. They can reduce their interest payments by redeem-

[bar graph - data below]

ARIZONA INTERMEDIATE-TERM MUNICIPAL'S
ONE-YEAR RETURNS SINCE INCEPTION (Periods ended November 30)

                     Arizona
                Intermediate-Term       Lehman 5-Year
                    Municipal             GO Index
11/94*               -0.27%                -0.07%
11/95                13.73%                11.99%
11/96                4.91%                 5.36%
11/97                5.02%                 5.38%

This graph  illustrates the fund's returns since its inception and compares them
with the index's  returns.  However,  the fund's  expenses  were waived  through
December  31,  1995.  Had these fees not been  waived,  returns  would have been
lower.  Starting in 1996, the fund's total returns include  operating  expenses,
while the  comparative  index's  returns do not. See page 20 for a definition of
the index.

Past  performance  is no  guarantee  of future  results.  Investment  return and
principal  value will fluctuate,  and redemption  value may be more or less than
original cost.

* Return from  4/30/94 (the date  nearest the fund's  inception  for which index
data are available) to 11/30/94.


SEMIANNUAL REPORT                                  MANAGEMENT Q & A       5


                                MANAGEMENT Q&A

ing  their  outstanding,  higher-yielding  bonds  and  issuing  new  ones at the
prevailing lower rates.

    As interest  rates fall, the fixed interest rate of a bond may become higher
than prevailing rates.  When this occurs,  there is an increased chance that the
issuer will call the bond prior to maturity.  As a result,  the  bond"trades  to
call"--the  market  prices the bond as if it will mature on its call date rather
than at its  scheduled  maturity.  If this happens to a large number of bonds in
the portfolio,  the fund's duration can shorten at a time when it should ideally
be longer to take advantage of rising bond prices.

    Because of this concern,  we frequently look to sell bonds before they trade
to call.

HAVE ANY OTHER TRENDS DEVELOPED RECENTLY IN THE MUNICIPAL MARKET?

    There's been a significant  increase in the supply of insured  bonds.  Lower
levels of new municipal issuance caused bond insurers to lower their premiums to
capture  more  business.  That  means that  issuers  have been able to raise the
credit rating of their bonds while paying a reduced insurance  premium. A higher
credit  rating on the bond  allows the  municipality  to offer a lower  interest
rate, saving them money in the long run.

    As a result,  investors  searching for  additional  yield  continued to show
strong  demand  for  lower-rated,  higher-yielding  municipal  securities.  This
diminished the yield advantage of these municipals.

HOW HAS THIS TREND AFFECTED THE FUND?

    It has made finding attractively  priced,  lower-rated issues more difficult
than ever.

    While we continue actively searching for bargains among lower-rated  issues,
the mainstay of the fund continues to be municipal  securities rated AAA and AA.
On the  positive  side,  this trend allows us to maintain a high level of credit
quality while sacrificing very little yield.

HOW ARE CREDIT CONDITIONS IN ARIZONA?

    Better,  thanks to strong economic growth during 1997. The state experienced
an increase  in new jobs,  pushing its  unemployment  rate to 5% by August.  Job
growth was most  impressive  in Phoenix and Tucson,  where  August  unemployment
rates fell to 2.8% and 3.3%, respectively.

    Migration  from  neighboring  high-cost  states,  an influx of retirees  and
higher personal  incomes in Arizona  translated into increased retail sales. The

[pie charts]

PORTFOLIO COMPOSITION BY SECURITY TYPE (as of 11/30/97)
GO                51%
Revenue Bonds     30%
COPs/Leases       12%
Land-Secured      4%
Prerefunded/ETM   3%

PORTFOLIO COMPOSITION BY SECURITY TYPE (as of 5/31/97)
GO                51%
Revenue Bonds     20%
COPs/Leases       12%
Prerefunded/ETM   10%
Land-Secured      7%


6       MANAGEMENT Q & A                         AMERICAN CENTURY INVESTMENTS


                                MANAGEMENT Q&A


steady  increase  in  taxable  sales  improved  the  state's  budget  and led to
improvement in overall municipal credit quality. A good example of this trend is
Maricopa County, which had its credit rating upgraded in 1997.

WHAT IS YOUR OUTLOOK FOR THE MUNICIPAL MARKET?

    We are cautiously  optimistic about the next six months.  Inflation  remains
tame,  having  risen by only  1.9% over the past  year.  "Real"  interest  rates
(nominal  interest  rates  minus the  inflation  rate) are at levels that should
inhibit inflation and economic growth. In addition,  strong  productivity  gains
should continue to offset wage gains in the near future.

    Economic  turmoil in Asia also means a reduced  chance for  inflation in the
U.S. Slower growth overseas could take the edge off U.S. economic growth because
it means less  business for U.S.  exporters.  And a strong U.S.  dollar and weak
Asian  currencies  means imported goods will be cheaper,  keeping overall prices
low.

    The  shrinking  federal  budget  deficit also boosts the Treasury  market by
reducing the supply of available  Treasury  securities.  Higher  Treasury prices
help  make  municipal   securities  a  better  relative  value,  which  supports
municipals by attracting more buyers.

WITH THIS OUTLOOK IN MIND, WHAT ARE YOUR PLANS FOR THE FUND GOING FORWARD?

    For now,  we'll  likely keep the fund's  duration  neutral to slightly  long
compared  with its peers.  That should  enhance the fund's  returns if municipal
bond  yields  continue to decline.  We will also  closely  watch the fund's call
risk.

    From a credit perspective,  we're monitoring  legislative  developments that
might change the way school districts issue debt in Arizona.  Though nothing has
been formally  decided yet on this issue, our credit research team is staying on
top of any changes that might affect the fund's holdings.

[pie charts]

PORTFOLIO COMPOSITION BY CREDIT RATING (as of 11/30/97)
AAA               51%
AA                33%
A                 8%
BBB               8%

PORTFOLIO COMPOSITION BY CREDIT RATING (as of 5/31/97)
AAA               54%
AA                28%
A                 9%
BBB               9%


SEMIANNUAL REPORT                                  MANAGEMENT Q & A       7

<TABLE>
<CAPTION>
                            SCHEDULE OF INVESTMENTS

NOVEMBER 30, 1997 (UNAUDITED)


Principal Amount                                                            Value
- --------------------------------------------------------------------------------------

MUNICIPAL SECURITIES

ARIZONA -- 96.9%

<S>             <C>                                                 <C>
                $1,000,000  Arizona Transportation Board
                                Excise Tax Rev., 7.00%, 7/1/99,
                                Prerefunded at 102% of Par
                                (MBIA)(1)                              $  1,064,790

                 1,000,000  Arizona Transportation Board
                                Excise Tax Rev., Series 1995 B,
                                (Maricopa County Regional Area),
                                5.50%, 7/1/99 (AMBAC)                     1,023,960

                 1,000,000  Arizona Transportation Board
                                Highway Rev., Series 1993 A,
                                6.00%, 7/1/08                             1,114,510

                 1,000,000  Arizona Water Infrastructure Finance
                                Auth. Rev., Series 1997 A,
                                5.00%, 7/1/14 (MBIA)                        993,270

                   900,000  Coconino & Yavapai County Joint
                                Unified School District No. 9 GO,
                                Series 1994 C, (Sedona Project),
                                5.60%, 7/1/06 (FGIC)                        948,339

                 1,000,000  East Valley Institute of Technology
                                District No. 401 GO,
                                Series 1996 B, 5.00%, 7/1/03
                                (AMBAC)                                   1,034,930

                   545,000  Gilbert County GO, Series 1994 C,
                                6.00%, 7/1/02 (MBIA)                        585,793

                 1,000,000  Maricopa County Community
                                College GO, Series 1995 A,
                                6.80%, 7/1/98                             1,017,490

                 1,000,000  Maricopa County Community
                                College GO, Series 1997 B,
                                5.25%, 7/1/10                             1,029,570

                   500,000  Maricopa County GO, 6.25%,
                                7/1/03 (FGIC)                               548,240

                 1,000,000  Maricopa County Hospital Rev.,
                                (Sun Health Corp.), 5.75%,
                                4/1/07                                    1,049,650

                   500,000  Maricopa County Industrial
                                Development Auth. Hospital
                                Facility Rev., (Samaritan Health
                                Services), 7.15%, 12/1/04
                                (MBIA)                                      579,960

                 2,000,000  Maricopa County Public Financing
                                Corporation Certificates of
                                Participation, 5.625%, 6/1/00             2,048,740


Principal Amount                                                            Value
- --------------------------------------------------------------------------------------

                $1,000,000  Maricopa County Unified School
                                District No. 1 GO, (Phoenix
                                Elementary), 5.50%, 7/1/09
                                (MBIA)                                 $  1,060,100

                 1,000,000  Maricopa County Unified School
                                District No. 6 GO, Series 1997 B,
                                (Washington Elementary),
                                4.75%, 7/1/11 (FGIC)                        979,370

                   800,000  Maricopa County Unified School
                                District No. 40 GO, Series 1995 C,
                                7.75%, 7/1/06 (FGIC)                        981,800

                 1,000,000  Maricopa County Unified School
                                District No. 41 GO, Series 1988 F,
                                (Gilbert), 6.20%, 7/1/02,
                                Prerefunded at 100% of
                                Par (FGIC)(1)                             1,079,870

                 1,000,000  Maricopa County Unified School
                                District No. 48 GO, (Scottsdale),
                                6.60%, 7/1/12                             1,176,260

                 1,000,000  Maricopa County Unified School
                                District No. 90 GO, (Ruth Fisher
                                Elementary), 5.375%, 7/1/00               1,027,420

                 1,000,000  Maricopa County Unified School
                                District No. 97 GO, Series 1996 A,
                                (Deer Valley), 6.25%, 7/1/06
                                (MBIA)                                    1,124,270

                 1,000,000  Maricopa County Unified School
                                District No. 201 GO,
                                Series 1992 E, (Phoenix),
                                7.10%, 7/1/04                             1,155,770

                   300,000  Phoenix Airport Rev., Series 1994 C,
                                5.50%, 7/1/01 (MBIA)                        312,459

                 1,000,000  Phoenix Civic Improvement Corp.
                                Wastewater System Lease Rev.,
                                4.85%, 7/1/07 (MBIA)                      1,014,130

                   550,000  Phoenix GO, 6.00%, 7/1/01                       584,359

                 1,000,000  Phoenix GO, Series 1995 B,
                                5.00%, 7/1/09                             1,018,910

                   500,000  Phoenix Street and Highway Rev.,
                                5.95%, 7/1/00                               523,005

                 1,000,000  Pima County Sewer Rev., 6.20%,
                                7/1/00 (FGIC)                             1,052,600

                 1,000,000  Pima County Unified School
                                District No. 10 GO,
                                (Amphitheater), 7.00%, 7/1/05
                                (MBIA)                                    1,164,810

                 1,000,000  Pima County Unified School
                                District No. 12 GO, (Sunnyside),
                                5.50%, 7/1/09 (MBIA)                      1,050,920

See Notes to Financial Statements


8      SCHEDULE OF INVESTMENTS                AMERICAN CENTURY INVESTMENTS


                            SCHEDULE OF INVESTMENTS

NOVEMBER 30, 1997 (UNAUDITED)


Principal Amount                                                            Value
- --------------------------------------------------------------------------------------

                $1,000,000  Salt River Project Agricultural
                                Improvement and Power District
                                Rev., Series 1993 B, 4.75%,
                                1/1/03                                $  1,020,340

                 1,000,000  Salt River Project Agricultural
                                Improvement and Power District
                                Rev., Series 1993 B, 6.50%,
                                1/1/04                                   1,113,360

                   480,000  Scottsdale GO, 7.50%, 7/1/02                   545,390

                 1,275,000  Tempe GO, 6.25%, 7/1/05                      1,424,035

                   525,000  Tucson Certificates of Participation,
                                5.70%, 7/1/02(2)                           533,741

                   200,000  Tucson Street and Highway Rev.,
                                4.50%, 7/1/98                              200,810

                 1,000,000  Tucson Street and Highway Rev.,
                                5.70%, 7/1/01                            1,050,840

                   500,000  Yavapai County Unified School
                                District No. 28 GO, (Camp Verde),
                                6.10%, 7/1/04 (FGIC)                       549,655
                                                                   ---------------------

                                                                        34,783,466
                                                                   ---------------------

PUERTO RICO -- 3.1%

                   500,000  Puerto Rico Commonwealth
                                Infrastructure Financing Auth. Rev.
                                Series 1998 A, 5.50%, 7/1/08
                                (AMBAC)(3)                                 531,225

                   500,000  Puerto Rico Public Buildings Auth.
                                Rev., Series 1995 A, 6.25%,
                                7/1/08 (AMBAC)                             568,530
                                                                   ---------------------

                                                                         1,099,755
                                                                   ---------------------

TOTAL INVESTMENT SECURITIES -- 100.0%                                  $35,883,221
                                                                   =====================
   (Cost $34,848,523)
</TABLE>


NOTES TO SCHEDULE OF INVESTMENTS

AMBAC = AMBAC Indemnity Corporation

FGIC = Financial Guaranty Insurance Co.

GO = General Obligation

MBIA = MBIA Insurance Corporation

(1) Escrowed to maturity in U.S. Government Securities.

(2) Denotes  security  which has been  segregated  at the  custodian  bank for a
    when-issued security.

(3) When-issued security.

See Notes to Financial Statements


SEMIANNUAL REPORT                          SCHEDULE OF INVESTMENTS        9


                      STATEMENT OF ASSETS AND LIABILITIES

NOVEMBER 30, 1997 (UNAUDITED)

ASSETS

Investment securities, at value
  (identified cost of $34,848,523)
   (Note 3) .......................................   $35,883,221

Interest receivable ...............................     831,745
                                                     --------------
                                                      36,714,966
                                                     --------------
LIABILITIES

Disbursements in excess of
  demand deposit cash .............................     111,161

Payable for investments purchased .................     528,025

Payable for capital shares redeemed ...............     32,611

Dividends payable .................................      9,179

Accrued management fees (Note 2) ..................     15,384
                                                     --------------
                                                        696,360
                                                     --------------
Net Assets ........................................   $36,018,606
                                                     ==============
CAPITAL SHARES

Outstanding (Unlimited number
  of shares authorized) ...........................    3,387,247
                                                     ==============
Net Asset Value Per Share .........................      $10.63
                                                     ==============
NET ASSETS CONSIST OF:

Capital paid in ...................................   $34,819,496

Accumulated undistributed net
  realized gain on investment
  transactions ....................................     164,412

Net unrealized appreciation
  on investments (Note 3) .........................    1,034,698
                                                     --------------
                                                      $36,018,606
                                                     ==============

See Notes to Financial Statements


10     STATEMENT OF ASSETS AND LIABILITIES     AMERICAN CENTURY INVESTMENTS


                            STATEMENT OF OPERATIONS

FOR THE SIX MONTHS ENDED NOVEMBER 30, 1997 (UNAUDITED)

INVESTMENT INCOME

Income:

Interest ..........................................      $   822,46
                                                       -------------
Expenses (Note 2):

Investment advisory fees ..........................         82,131

Printing and postage ..............................         11,971

Custodian fees ....................................          5,525

Administrative fees ...............................          4,889

Registration and filing fees ......................          3,497

Transfer agency fees ..............................          3,255

Trustees' fees and expenses .......................          1,164

Auditing and legal fees ...........................          1,081

Organizational expenses ...........................           168

Other operating expenses ..........................          2,809
                                                       -------------
  Total expenses ..................................         116,490

Amount waived .....................................        (21,161)
                                                       -------------
  Net expenses ....................................         95,329
                                                       -------------
Net investment income .............................         727,140
                                                       -------------
REALIZED AND UNREALIZED GAIN
ON INVESTMENTS (NOTE 3)

Net realized gain on investments ..................         164,990

Change in net unrealized
  appreciation on investments .....................         424,673
                                                       -------------
Net realized and unrealized
gain on investments ...............................         589,663
                                                       -------------
Net Increase in Net Assets
Resulting from Operations .........................      $1,316,803
                                                       =============
See Notes to Financial Statements


SEMIANNUAL REPORT                           STATEMENT OF OPERATIONS       11


                      STATEMENTS OF CHANGES IN NET ASSETS

SIX MONTHS ENDED NOVEMBER 30, 1997 (UNAUDITED)
AND YEAR ENDED MAY 31, 1997

                                                 November 30,          May 31,
Increase in Net Assets                               1997               1997

OPERATIONS

Net investment income ......................... $  727,140          $ 1,207,103

Net realized gain on investment
  transactions ................................    164,990             12,678

Change in net unrealized
  appreciation on investments .................    424,673             303,847
                                               -------------        ------------
Net increase in net assets
  resulting from operations ...................   1,316,803           1,523,628
                                               -------------        ------------
DISTRIBUTIONS TO
SHAREHOLDERS

From net investment income ....................    (727,140)         (1,207,103)
                                               -------------        ------------
CAPITAL SHARE TRANSACTIONS

Proceeds from shares sold .....................   7,799,513          15,353,294

Proceeds from reinvestment
  of distributions ............................    540,257             917,406

Payments for shares redeemed ..................  (3,465,390)        (11,821,630)
                                               -------------        ------------
Net increase in net assets from
  capital share transactions ..................   4,874,380           4,449,070
                                               -------------        ------------
Net increase in net assets ....................   5,464,043           4,765,595

NET ASSETS

Beginning of period ...........................   30,554,563         25,788,968
                                               -------------        ------------
End of period .................................  $36,018,606         $30,554,563
                                               =============        ============
TRANSACTIONS IN SHARES
OF THE FUND

Sold ..........................................    736,745            1,472,637

Issued in reinvestment of
  distributions ...............................     50,945             88,040

Redeemed ......................................   (327,417)          (1,134,039)
                                               -------------        ------------
Net increase ..................................    460,273             426,638
                                               =============        ============
See Notes to Financial Statements


12      STATEMENTS OF CHANGES IN NET ASSETS    AMERICAN CENTURY INVESTMENTS


                         NOTES TO FINANCIAL STATEMENTS

NOVEMBER 30, 1997 (UNAUDITED)

1. ORGANIZATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES

    ORGANIZATION--American  Century  Municipal  Trust (the Trust) is  registered
under the Investment  Company Act of 1940 as an open-end  management  investment
company. American Century - Benham Arizona Intermediate-Term Municipal Fund (the
Fund) is one of the seven funds issued by the Trust. The Fund is non-diversified
under  the 1940  Act.  The  objective  of the Fund is to seek as high a level of
current  income exempt from federal  income taxes as is consistent  with prudent
investment  management  and  conservation  of  shareholders'  capital.  The Fund
invests primarily in Arizona intermediate-term  municipal obligations.  The Fund
concentrates  its  investments  in a single  state and  therefore  may have more
exposure  to credit  risk  related  to the state of  Arizona  than a fund with a
broader  geographical  diversification.  The  following  significant  accounting
policies  related  to  the  Fund  are in  accordance  with  accounting  policies
generally accepted in the investment company industry.

    SECURITY  VALUATIONS--Portfolio  securities  are valued  through  valuations
obtained from a commercial pricing service or at the mean of the most recent bid
and asked prices.  When  valuations  are not readily  available,  securities are
valued at fair value as determined in accordance with procedures  adopted by the
Board of Trustees.

    SECURITY  TRANSACTIONS--Security  transactions are accounted for on the date
purchased  or  sold.  Net  realized  gains  and  losses  are  determined  on the
identified cost basis, which is also used for federal income tax purposes.

    INVESTMENT  INCOME--Interest  income is recorded  on the  accrual  basis and
includes accretion of discounts and amortization of premiums.

    INCOME TAX  STATUS--It is the Fund's policy to distribute all net investment
income and net realized capital gains to shareholders  and to otherwise  qualify
as a regulated  investment  company under the provisions of the Internal Revenue
Code. Accordingly, no provision has been made for federal or state taxes.

    DISTRIBUTIONS TO SHAREHOLDERS--Distributions  from net investment income are
declared daily and distributed  monthly.  Distributions  from net realized gains
are declared and paid annually.

    The  character  of  distributions  made during the year from net  investment
income or net realized gains may differ from their ultimate characterization for
federal income tax purposes due to differences in the  recognition of income and
expense items for financial reporting and tax purposes.

    FUTURES CONTRACTS--The Fund may buy and sell interest rate futures contracts
relating to debt  securities and write and buy put and call options  relating to
interest  rate  futures  contracts.   The  Fund  may  use  futures  and  options
transactions  to maintain cash  reserves  while  remaining  fully  invested,  to
facilitate  trading, to reduce transaction costs, or to pursue higher investment
returns when a futures contract is priced more  attractively than its underlying
security  or index.  One of the risks of entering  into  futures  contracts  may
include  the  possibility  that the  changes  in value of the  contract  may not
correlate with the changes in value of the underlying securities.  Upon entering
into a  futures  contract,  the  Fund is  required  to  deposit  either  cash or
securities  in an amount equal to a certain  percentage  of the  contract  value
(initial margin).  Subsequent  payments  (variation margin) are made or received
daily,  in cash, by the Fund. The variation  margin is equal to the daily change
in the contract  value and is recorded as an unrealized  gain or loss.  The Fund
recognizes a realized gain or loss when the contract is closed or expires. There
were no open futures contracts at November 30, 1997.

    USE OF ESTIMATES--The preparation of financial statements in conformity with
generally accepted  accounting  principles requires management to make estimates
and assumptions  that affect the reported  amounts of assets and liabilities and
disclosure of  contingent  assets and  liabilities  at the date of the financial
statements  and the reported  amounts of increases  and  decreases in net assets
from  operations  during the  period.  Actual  results  could  differ from these
estimates.


SEMIANNUAL REPORT                     NOTES TO FINANCIAL STATEMENTS       13


                         NOTES TO FINANCIAL STATEMENTS

NOVEMBER 30, 1997 (UNAUDITED)
- --------------------------------------------------------------------------------

2. TRANSACTIONS WITH RELATED PARTIES

    The  shareholders  of the Fund  approved  a new  management  agreement  with
American Century Investment Management,  Inc. (ACIM) on July 30, 1997, effective
August 1, 1997,  which  replaced  the  existing  contracts  between the Fund and
Benham Management  Corporation and American Century Services  Corporation (ACSC)
for advisory,  administrative  and transfer agency services.  Expenses  excluded
from the agreement are brokerage, taxes, portfolio insurance, interest, fees and
expenses of the Trustees who are not considered  "interested persons" as defined
in the Investment Company Act of 1940 (including counsel fees) and extraordinary
expenses.  Under the agreement,  ACIM will provide all services  required by the
Fund in exchange for one unified  management  fee. The annual rate at which this
fee is assessed is determined  monthly in a two-step process:  First, a fee rate
schedule  is applied to the assets of all of the funds in the Fund's  investment
category which are managed by ACIM (the "Investment  Category Fee"). The overall
investment objective of each Fund determines its Investment Category.  The three
investment  categories  are:  the  Money  Market  Fund  Category,  the Bond Fund
Category,  and the Equity Fund  Category.  The Fund is included in the Bond Fund
Category.  Second,  a separate fee rate schedule is applied to the assets of all
of the funds managed by ACIM (the "Complex  Fee").  The Investment  Category Fee
and the Complex Fee are then added to determine the unified management fee rate.
The  management  fee is paid monthly by the Fund based on its aggregate  average
daily net assets during the previous month multiplied by the monthly  management
fee rate.

The annualized Investment Category Fee schedule for the Fund is as follows:

     0.2800% of the first $1 billion 
     0.2280% of the next $1 billion 
     0.1980% of the next $3 billion 
     0.1780% of the next $5 billion 
     0.1650% of the next $15 billion
     0.1630% of the next $25 billion
     0.1625% of the average daily net assets over $50 billion

The annualized Complex Fee schedule is as follows:

     0.3100% of the first $2.5 billion 
     0.3000% of the next $7.5 billion 
     0.2985% of the next $15 billion 
     0.2970% of the next $25 billion 
     0.2960% of the next $50 billion 
     0.2950% of the next $100 billion 
     0.2940% of the next $100 billion
     0.2930% of the next $200 billion 
     0.2920% of the next $250 billion 
     0.2910% of the next $500 billion
     0.2900% of the average daily net assets over $1,250 billion

    Management fees of $59,410 were incurred under the new management  agreement
and included in Investment  Advisory Fees in the Statement of Operations.  Total
expenses (net of amount waived) and the annualized  ratio of operating  expenses
to average net assets,  under the previous  agreement,  for the two months ended
July 31, 1997 were $35,083 and 0.67%, respectively.

    Certain  officers  and  trustees  of the  Trust  are  also  officers  and/or
directors,  and,  as a  group,  controlling  stockholders  of  American  Century
Companies, Inc., the parent of the Trust's investment manager, ACIM, the Trust's
transfer  agent,  ACSC,  and  the  registered  broker-dealer,  American  Century
Investment Services, Inc.

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

3. INVESTMENT TRANSACTIONS

    Purchases  and sales of municipal  debt  obligations,  excluding  short-term
investments, totaled $13,833,885 and $8,077,835, respectively.

    As of  November  30,  1997,  accumulated  net  unrealized  appreciation  was
$1,034,698,  consisting of unrealized  appreciation of $1,040,516 and unrealized
depreciation of $5,818. The aggregate cost of investments for federal income tax
purposes was the same as the cost for financial reporting purposes.


14      NOTES TO FINANCIAL STATEMENTS          AMERICAN CENTURY INVESTMENTS


<TABLE>
<CAPTION>
                             FINANCIAL HIGHLIGHTS

    For a Share Outstanding Throughout the Years Ended May 31 (except as noted)

                                           1997(1)              1997             1996            1995           1994(2)

PER-SHARE DATA

Net Asset Value,
<S>                                     <C>            <C>             <C>            <C>            <C>   
Beginning of Period ..............     $    10.44          $    10.31       $    10.35       $    10.13       $   10.00
                                       ----------          ----------       ----------       ----------       ---------
Income From Investment Operations

  Net Investment Income ..........           0.23                0.45             0.51             0.51            0.07

  Net Realized and Unrealized
  Gain (Loss)
  on Investment Transactions .....           0.19                0.13            (0.03)            0.22            0.13
                                       ----------          ----------       ----------       ----------       ---------
  Total From Investment Operations           0.42                0.58             0.48             0.73            0.20
                                       ----------          ----------       ----------       ----------       ---------
Distributions

  From Net Investment Income .....          (0.23)              (0.45)           (0.51)           (0.51)          (0.07)

  From Net Realized Gains on
  Investment Transactions ........           --                  --              (0.01)            --              --
                                       ----------          ----------       ----------       ----------       ---------
  Total Distributions ............          (0.23)              (0.45)           (0.52)           (0.51)          (0.07)
                                       ----------          ----------       ----------       ----------       ---------
Net Asset Value, End of Period ...     $    10.63          $    10.44       $    10.31       $    10.35       $   10.13
                                       ==========          ==========       ==========       ==========       =========
  Total Return(3) ................           4.04%               5.77%            4.65%            7.52%           1.99%

RATIOS/SUPPLEMENTAL DATA

Ratio of Operating Expenses
to Average Net Assets ............           0.57%(4)            0.66%            0.14%            --              --

Ratio of Operating Expenses to
AverageNet Assets
(Before Expense Waiver) ..........           0.69%(4)            0.79%            0.82%            1.01%           2.33%(4)

Ratio of Net Investment
Income to Average Net Assets .....           4.33%(4)            4.35%            4.85%            5.16%           5.08%(4)

Ratio of Net Investment Income
to Average Net Assets
(Before Expense Waiver) ..........           4.20%(4)            4.22%            4.17%            4.15%           2.75%(4)

Portfolio Turnover Rate ..........             24%                 81%              36%              33%             18%

Net Assets, End
of Period (in thousands) .........     $   36,019          $   30,555       $   25,789       $   19,778       $   7,187
</TABLE>
- ----------

(1) Six months ended November 30, 1997 (unaudited).

(2) April 11, 1994 (inception) through May 31, 1994.

(3) Total  return   assumes   reinvestment   of  dividends   and  capital  gains
    distributions,  if any. Total returns for periods less than one year are not
    annualized.

(4) Annualized.

See Notes to Financial Statements


SEMIANNUAL REPORT                              FINANCIAL HIGHLIGHTS       15


                             PROXY VOTING RESULTS

    An annual meeting of shareholders  was held on July 30, 1997, to vote on the
following  proposals.  All of the  proposals  received the required  majority of
votes and were adopted.

    A summary of voting results is listed below each proposal.

PROPOSAL 1:

    To vote on the selection by the Board of Trustees of Coopers & Lybrand
L.L.P. as independent auditors for the Trust.

    For:                               1,691,673
    Against:                            98,911
    Abstain:                            21,418


PROPOSAL 2:

    To vote on the  approval of a Management  Agreement  with  American  Century
Investment Management, Inc.

    For:                               1,683,019
    Against:                            107,041
    Abstain:                            21,942


PROPOSAL 3:

    To vote on the adoption of standardized investment limitations.

*  Amend the fundamental investment limitation concerning borrowing.

    For:                               1,582,354
    Against:                            186,401
    Abstain:                            28,803
    Broker Non-Vote:                    14,444

*  Amend the fundamental investment limitation concerning lending.

    For:                               1,585,397
    Against:                            184,062
    Abstain:                            28,099
    Broker Non-Vote                     14,444

*  Amend the fundamental investment limitation concerning commodities.

    For:                               1,567,545
    Against:                            193,735
    Abstain:                            36,278
    Broker Non-Vote:                    14,444

*  Eliminate the fundamental  investment  limitation  concerning  investments in
   oil, gas and mineral exploration development programs.

    For:                               1,572,814
    Against:                            197,021
    Abstain:                            27,723
    Broker Non-Vote:                    14,444


16      PROXY VOTING RESULTS                   AMERICAN CENTURY INVESTMENTS


                                     NOTES


SEMIANNUAL REPORT                                             NOTES       17


                                     NOTES


18      NOTES                                  AMERICAN CENTURY INVESTMENTS


                                     NOTES


SEMIANNUAL REPORT                                             NOTES       19


                            BACKGROUND INFORMATION

INVESTMENT PHILOSOPHY & POLICIES

    The Benham Group  offers 38  fixed-income  funds,  ranging from money market
funds to long-term bond funds and including  both taxable and tax-exempt  funds.
Each fund is  managed  to  provide  a "pure  play" on a  specific  sector of the
fixed-income market. To ensure adherence to this principle,  the basic structure
of each fund's  portfolio  is tied to a specific  market  index.  Fund  managers
attempt  to add  value by making  modest  portfolio  adjustments  based on their
analysis of  prevailing  market  conditions.  Investment  decisions  are made by
management teams, which meet regularly to discuss market analysis and investment
strategies.

    In addition to these principles, each fund has its own investment policies:

    ARIZONA INTERMEDIATE-TERM  MUNICIPAL seeks to provide interest income exempt
from both  Arizona and federal  income  taxes.  The fund  invests  primarily  in
intermediate-term  Arizona municipal  securities with maturities of four or more
years and maintains a weighted average maturity of 5-10 years.

    Depending  on your tax  status,  investment  income  may be  subject  to the
federal  alternative  minimum  tax.  Capital  gains are not exempt from  federal
income tax.

COMPARATIVE INDICES

    The index  listed  below is used in the report to serve as fund  performance
comparisons. It is not an investment product available for purchase.

    The LEHMAN 5-YEAR  MUNICIPAL  GENERAL  OBLIGATION  INDEX is a municipal bond
index  composed of more than 11,000 bonds with  maturities of four to six years.
The bonds are rated BBB or higher by Standard & Poor's,  with an average  rating
of AA. The average maturity of the index is five years.

LIPPER RANKINGS

    LIPPER  ANALYTICAL  SERVICES,  INC. is an  independent  mutual fund  ranking
service.  Rankings are based on average  annual total returns for each fund in a
given category for the periods indicated.  Rankings are not included for periods
less than one year.

    The  funds in  Lipper's  OTHER  STATES  INTERMEDIATE  MUNICIPAL  DEBT  FUNDS
category invest in municipal debt issues with dollar-weighted average maturities
of 5-100 years and which are exempt from  taxation on a specified  city or state
basis.

INVESTMENT TEAM LEADERS

  Portfolio Manager                          Colleen Denzler

  Credit Research Manager                    Steven Permut


20      BACKGROUND INFORMATION                 AMERICAN CENTURY INVESTMENTS


                                   GLOSSARY

RETURNS

* TOTAL  RETURN  figures  show the overall  percentage  change in the value of a
hypothetical  investment  in  the  fund  and  assume  that  all  of  the  fund's
distributions are reinvested.

* AVERAGE ANNUAL RETURNS  illustrate the annually  compounded returns that would
have produced the fund's cumulative total returns if the fund's  performance had
been  constant  over the  entire  period.  Average  annual  returns  smooth  out
variations  in a fund's  return;  they are not the same as  fiscal  year-by-year
results.  For  fiscal  year-by-year  returns,  please  refer  to the  "Financial
Highlights" on page 15.

YIELDS

* 30-DAY SEC YIELD  represents net  investment  income earned by the fund over a
30-day period,  expressed as an annual percentage rate based on the fund's share
price at the end of the 30-day  period.  The SEC yield  should be regarded as an
estimate of the fund's investment income, and it may not equal the fund's actual
income  distribution  rate, the income paid to a shareholder's  account,  or the
income reported in the fund's financial statements.

*  TAX-EQUIVALENT  YIELDS show the taxable  yields that  investors in a combined
federal and Arizona  state income tax bracket would have to earn before taxes to
equal the fund's tax-free yield.

INVESTMENT TERMS

* BASIS POINT--a basis point equals one  one-hundredth of a percentage point (or
0.01%). Therefore, 100 basis points equals one percentage point (or 1%).

* YIELD CURVE--a graphic representation of the relationship between maturity and
yield  for  fixed-income   securities.   Yield  curve  graphs  plot  lengthening
maturities along the horizontal axis and rising yields along the vertical axis.

PORTFOLIO STATISTICS

* NUMBER OF SECURITIES--the  number of different  securities issuances held by a
fund on a given date.

*  WEIGHTED  AVERAGE  MATURITY  (WAM)--a  measurement  of the  sensitivity  of a
fixed-income  portfolio to interest rate changes. WAM indicates the average time
until the securities in the portfolio mature, weighted by dollar amount.

*  AVERAGE  DURATION--another  measure  of  the  sensitivity  of a  fixed-income
portfolio to interest rate changes.  Duration is a time-weighted  average of the
interest and principal payments of the securities in a portfolio.

* EXPENSE RATIO--the  operating expenses of the fund,  expressed as a percentage
of average net assets.  Shareholders pay an annual fee to the investment manager
for  investment  advisory  and  management  services.  The expenses and fees are
deducted from fund income, not from each shareholder's account.

TYPES OF MUNICIPAL SECURITIES

*  COPS/LEASES--securities  issued to finance public property improvements (such
as city halls and police  stations) and  equipment  purchases.  Certificates  of
participation  represent long-term debt obligations,  while leases have a higher
risk profile than GOs because they require annual appropriation.

* GO  BONDS--general  obligation  securities  backed by the taxing  power of the
issuer.

*  LAND-SECURED  BONDS--securities  such as Mello-Roos  bonds and 1915-Act bonds
that are issued to finance real estate development projects.

* PREREFUNDED BONDS/ETM BONDS--securities  refinanced or escrowed to maturity by
the issuer because of their premium coupons (higher-than-market interest rates).
These  bonds  tend to have  higher  credit  ratings  because  they are backed by
Treasury securities.

*  REVENUE  BONDS--securities  backed by  revenues  from  sales  taxes or from a
specific  project,  system or facility (such as a hospital,  electric utility or
water system).


SEMIANNUAL REPORT                                          GLOSSARY       21

[american century logo]
American
Century(reg.sm)

P.O. BOX 419200
KANSAS CITY, MISSOURI
64141-6200

INVESTOR SERVICES:
1-800-345-2021 OR 816-531-5575

AUTOMATED INFORMATION LINE:
1-800-345-8765

TELECOMMUNICATIONS DEVICE FOR THE DEAF:
1-800-634-4113 OR 816-444-3485

FAX: 816-340-7962

INTERNET: WWW.AMERICANCENTURY.COM


AMERICAN CENTURY MUNICIPAL TRUST


INVESTMENT MANAGER

AMERICAN CENTURY INVESTMENT MANAGEMENT, INC.

KANSAS CITY, MISSOURI


THIS REPORT AND THE STATEMENTS IT CONTAINS ARE SUBMITTED FOR THE GENERAL
INFORMATION OF OUR SHAREHOLDERS. THE REPORT IS NOT AUTHORIZED FOR DISTRIBUTION
TO PROSPECTIVE INVESTORS UNLESS PRECEDED OR ACCOMPANIED BY AN EFFECTIVE
PROSPECTUS.


(c) 1998 AMERICAN CENTURY SERVICES CORPORATION FUNDS DISTRIBUTOR, INC.


9801           [recycled logo]
SH-BKT-10689      Recycled
<PAGE>
                                  SEMIANNUAL
                                    REPORT

                            [american century logo]
                                    American
                                Century(reg.sm)


                               NOVEMBER 30, 1997

                                    BENHAM
                                     GROUP

                             Tax-Free Money Market

                               TABLE OF CONTENTS

Report Highlights .......................................................      1
Our Message to You ......................................................      2
Performance & Portfolio Information .....................................      3
Management Q & A ........................................................      4
Schedule of Investments .................................................      6
Statement of Assets and Liabilities .....................................     11
Statement of Operations .................................................     12
Statements of Changes in Net Assets .....................................     13
Notes to Financial Statements ...........................................     14
Financial Highlights ....................................................     16
Proxy Voting Results ....................................................     17
Background Information
           Investment Philosophy & Policies .............................     20
           Lipper Rankings ..............................................     20
           Investment Team Leaders ......................................     20

Glossary ................................................................     21

       American Century  Investments  offers you nearly 70 fund choices covering
stocks,  bonds,  money markets,  specialty  investments and blended  portfolios.
We've organized our funds into three distinct groups,  based on investment style
and objectives, to help simplify your fund decisions. These groups appear below.


                  AMERICAN CENTURY INVESTMENTS--FAMILY OF FUNDS
- -------------------------------------------------------------------------------
        Benham                American Century       Twentieth Century(reg. tm)
     Group(reg. tm)                 Group                      Group
- -------------------------------------------------------------------------------
   MONEY MARKET FUNDS         ASSET ALLOCATION &           GROWTH FUNDS
 GOVERNMENT BOND FUNDS          BALANCED FUNDS          INTERNATIONAL FUNDS
 DIVERSIFIED BOND FUNDS   CONSERVATIVE EQUITY FUNDS
  MUNICIPAL BOND FUNDS         SPECIALTY FUNDS
- -------------------------------------------------------------------------------
       Tax-Free
     Money Market

We welcome your comments or questions about this report.  
See the back cover for ways to contact us by mail, phone or e-mail.

Twentieth  Century and American Century are registered marks of American Century
Services  Corporation.  Benham Group is a registered  mark of Benham  Management
Corporation.


                          AMERICAN CENTURY INVESTMENTS


                               REPORT HIGHLIGHTS

MUNICIPAL MARKET PERSPECTIVE

*   The Federal  Reserve held  short-term  interest  rates steady during the six
    months ended November 30, 1997.

*   Low inflation and strong demand contributed to lower yields overall.

*   Credit spreads fell to historically  low levels because of improving  credit
    quality and the increase in the number of municipal  securities insured with
    a AAA rating.

TAX-FREE MONEY MARKET

*   The fund  significantly  outperformed the average tax-free money market fund
    during the six months ended November 30, 1997.

*   While past  performance is no guarantee of future results,  the fund had the
    highest 7-day current yield of 141 "Stockbroker and General Purpose Tax-Free
    Money Funds" on December 1, according to IBC's Money Fund Report

*   Beginning August 1, 1997,  American  Century waived  management fees for one
    year, which helped boost the fund's yield.

*   As of December,  the fund had no exposure to Japanese  banks,  which provide
    credit backing for many municipal money market securities.

*   Going forward,  we'll continue to use a value-oriented  approach to security
    selection,  buying  one-year  notes when we think they provide  sufficiently
    higher yields than shorter-term securities.


                 TAX-FREE
               MONEY MARKET

TOTAL RETURNS:              AS OF 11/30/97
     6 Months                       1.82%*
     1 Year                           3.36%

7-DAY CURRENT YIELD:                  4.04%

NET ASSETS:                 $194.8 million
     (AS OF 11/30/97)

INCEPTION DATE:                     7/31/84

TICKER SYMBOL:                        BNTXX

* Not annualized.


SEMIANNUAL REPORT                                 REPORT HIGHLIGHTS       1


                              OUR MESSAGE TO YOU

              [photo of James E. Stowers III and James M. Benham]

    The Benham  Tax-Free  Money Market fund performed well during the six months
ended  November  30,  1997,  rewarding  investors  with a  competitive  level of
tax-free income.  According to IBC's Money Fund Report,  as of December 1, 1997,
Benham Tax-Free was the  highest-yielding  tax-free money market fund out of 141
funds.  On the  following  pages,  our municipal  investment  team provides more
details on the fund's performance.

    On the  corporate  front,  the latter half of 1997  proved as  eventful  for
American  Century as it was for  investors.  In July,  J.P.  Morgan & Co.,  Inc.
agreed to become a significant minority shareholder in our company. Through this
business  partnership,  we  see  many  opportunities  to  expand  the  range  of
investment  choices and services we offer you. J.P.  Morgan has been in business
for more than 150 years, serving institutions,  governments and individuals with
complex  financial needs.  Within the framework of this  relationship,  American
Century  will  continue  to operate as an  independent  company.  Our  corporate
management  team will remain the same, and the Stowers family will retain voting
control of the company.

    On a more  personal  note,  1997 was the year we said  farewell  to James M.
Benham,  founder of the Benham Group of mutual funds. Mr. Benham,  who announced
his  retirement in December,  was a pioneer in the no-load  mutual fund industry
and the father of Capital  Preservation  Fund,  the first money  market fund for
individual  investors.  With the  integration  of Benham and  Twentieth  Century
successfully  completed,  Mr.  Benham  felt it was  time to step  back  from the
business and enjoy a well-earned retirement,  confident that he leaves the funds
he founded in very  capable  hands.  Though his  counsel  and  guidance  will be
missed,  much of the  Benham  culture  has  become a part of  American  Century,
including the educational  investor seminar program Mr. Benham created.  And two
of his sons,  Jim A. Benham and Tim Benham,  remain with the company to carry on
the Benham tradition.

    Looking  forward,  1998 will be a  landmark  year for us,  marking  the 40th
anniversary of the introduction of our first two funds, Twentieth Century Growth
and  Twentieth  Century  Select.  Not many fund  companies  have a 40-year track
record, nor have many built a fund family such as ours, which includes nearly 70
stock,  bond,  money and  combination  funds that provide  investors with a wide
range of choice and flexibility.

    Whatever your financial  goals, we believe we have an outstanding  lineup of
funds to help you pursue them.

    Sincerely,

/s/James E. Stowers III                  /s/James M. Benham
James E. Stowers III                     James M. Benham
Chief Executive Officer                  Vice Chairman
American Century Investment              American Century Investment
   Management, Inc.                         Management, Inc


2      OUR MESSAGE TO YOU                     AMERICAN CENTURY INVESTMENTS


<TABLE>
<CAPTION>
                      PERFORMANCE & PORTFOLIO INFORMATION

                                     7-DAY           7-DAY                         7-DAY TAX-EQUIVALENT YIELDS
                                    CURRENT        EFFECTIVE          28%              31%             36%              39.6%
                                     YIELD           YIELD        Tax Bracket      Tax Bracket     Tax Bracket  Tax Bracket
- ------------------------------------------------------------------------------------------------------------------------------------
YIELDS AS OF NOVEMBER 30, 1997

<S>                                  <C>             <C>             <C>              <C>             <C>               <C>  
Tax-Free Money Market                4.04%           4.12%           5.61%            5.86%           6.31%             6.69%


                                                                                              AVERAGE ANNUAL RETURNS
                                                   6 MONTHS         1 YEAR           3 YEARS         5 YEARS          10
YEARS
- ------------------------------------------------------------------------------------------------------------------------------------

 TOTAL RETURNS AS OF NOVEMBER 30, 1997(1)

Tax-Free Money Market .............................  1.82%            3.36%           3.24%           2.77%             3.72%

Average Tax-Exempt Money Market Fund(2) ...........  1.55%            3.06%           3.13%           2.70%             3.66%

Fund's Ranking Among
Tax-Exempt
Money Market Funds(2) .............................   --          8 out of 135    30 out of 118   30 out of 97      19 out of 61
</TABLE>
- ----------

(1) Returns for periods less than one year are not annualized.

(2) According to Lipper Analytical Services.

See pages 20-21 for more information about returns and Lipper fund rankings.


PORTFOLIO AT A GLANCE
                                 11/30/97      5/31/97
Number of Securities                73           48
Weighted Average Maturity         47 days      53 days
Expense Ratio                     0.18%*        0.67%

* Annualized.  On August 1, 1997, American Century Investment  Management,  Inc.
began waiving the fund's  management  fees.  Without the fee waiver,  the fund's
7-day   current  and   effective   yields  would  have  been  3.54%  and  3.60%,
respectively.  The 7-day  tax-equivalent  yields for the 28%, 31%, 36% and 39.6%
tax brackets would have been 4.92%, 5.13%, 5.53% and 5.86%, respectively.

Money market funds are neither insured nor guaranteed by the U.S. government.

Yields will fluctuate,  and there can be no assurance that the fund will be able
to maintain a stable $1.00 share price.

Past performance does not guarantee future results.

Many of the investment  terms in this report are defined in the Glossary on page
21.


SEMIANNUAL REPORT               PERFORMANCE & PORTFOLIO INFORMATION       3


                                MANAGEMENT Q&A

    An interview with Bryan Karcher,  a portfolio  manager on the Tax-Free Money
Market fund investment team.

HOW DID THE FUND PERFORM DURING THE SIX MONTHS ENDED NOVEMBER 30, 1997?

    The fund  performed  very well,  providing a much higher level of tax-exempt
income than the average tax-free money market fund. For the six months, the fund
had a total return of 1.82%,  compared with the 1.55% average  return of the 136
"Tax-Exempt Money Market Funds" tracked by Lipper Analytical Services.  (See the
Total  Returns   table  on  the  previous   page  for  other  fund   performance
comparisons.)  According  to IBC's Money Fund Report,  the fund's 7-day  current
yield as of  December  1 was the  highest  among 141 "Stock  Broker and  General
Purpose Tax-Free Money Funds."

    We didn't take additional  credit risk or invest in risky derivatives to get
that  yield--rather,  we waived our management fee as part of a  straightforward
promotion.

CAN YOU EXPLAIN THE CHANGES TO THE FUND'S MANAGEMENT FEE?

    Sure.  American  Century  Investment  Management,  Inc.  (ACIM)  waived  its
management  fee for one year,  beginning  August 1,  1997.  The  absence of fees
helped  significantly boost the fund's yield. We also lowered the fund's expense
ratio from 61 basis points  before the waiver to  approximately  50 basis points
beginning in August 1998, or from 0.61% to 0.50%.

    But it's  important to note that we're not going to re-impose the entire fee
on August 1,  1998.  Instead,  ACIM plans to phase in  expenses  at a rate of 10
basis points per month.  At that rate,  the fund will reach its expense ratio of
approximately 0.50% in December 1998.

    And even with full  expenses,  we  anticipate  the fund will have one of the
lowest expense  ratios among tax-free money market funds.  The new fee structure
directly  benefits   shareholders  because  we're  delivering  the  same  strong
performance,  but at a lower cost. Other things being equal, lower expenses mean
higher returns and yields for our shareholders.

HOW DID YOU POSITION THE FUND DURING THE PERIOD?

    Finding  longer-maturity,  higher-yielding  securities was difficult because
short-term  securities had almost the same yields as longer-term  securities for
much of the period.  Inflation  remained under control,  and the likelihood that
the Federal Reserve would raise interest rates diminished. That caused the yield
curve  between  three  months and one year to  flatten--the  yields on  one-year
Treasury  notes  dropped,  bringing the spread (or  difference in yield) between
three-month and one-year Treasurys to 25 basis points, or 0.25%.

    As a result,  we allowed the fund's average maturity to shorten to around 30
days in  September,  rather than  purchase  one-year  notes that we felt weren't
offering  sufficiently  higher  yields than  shorter-term  securities.  However,
one-year notes began to offer

[pie charts]

PORTFOLIO COMPOSITION BY SECURITY TYPE (as of 11/30/97)
VRDNs                 78%
Bonds less than 1 Year 9%
Municipal Notes        6%
Commercial Paper       2%
Other                  5%


PORTFOLIO COMPOSITION BY SECURITY TYPE (as of 5/31/97)
VRDNs                       59%
Bonds less than 1 Year      16%
Commercial Paper            15%
Municipal Notes             10%


4      MANAGEMENT Q & A                         AMERICAN CENTURY INVESTMENTS


                                MANAGEMENT Q&A


additional  yield in October and  November,  so we extended  the fund's  average
maturity out beyond 60 days. Nevertheless,  the fund's maturity ended the period
at less than 50 days because we invested  large cash inflows in late November in
relatively short-term variable-rate notes (floaters).

HOW DO YOU DECIDE WHEN A ONE-YEAR SECURITY IS A GOOD BUY?

    First,  we  look  at  how  much  additional  yield  we  anticipate  one-year
securities  will offer versus  weekly  floaters,  given our outlook for interest
rates. That helps us determine if we're being compensated with enough additional
yield to justify extending the fund's average maturity.

    Second, we look at the relative value of one-year municipal  securities as a
percentage of Treasurys. This provides a second measure of the attractiveness of
one-year  municipal  paper.  We know one-year  paper is more likely to be a good
value when both of these  indicators  are positive,  as they were in October and
November.

HOW DO JAPANESE BANKS AFFECT THE FUND'S PORTFOLIO?

    Many  municipal  money  market  securities  are  backed by letters of credit
(LOCs) from banks,  including  Japanese banks.  Over the last several years, the
Japanese  banking  system has suffered  from a lengthy  domestic  recession  and
non-performing real estate loans.

    Consistent with our strict municipal credit criteria,  over the last year we
reduced the number of Japanese banks whose  obligations we approve for purchase.
As of  December,  the fund no longer  owned any  securities  backed by  Japanese
banks.

WHAT'S YOUR OUTLOOK FOR INTEREST RATES OVER THE NEXT SIX MONTHS?

    We think the outlook for interest rates is relatively stable. The economy is
fairly strong,  but inflation remains low, so we don't see a call for Fed action
on interest  rates  either way in the near  future.  However,  supply and demand
factors in the  municipal  money  market  seem to argue for lower  yields  after
year's end. The first quarter tends to bring lower yields because there are many
buyers in the market at a time when there is little new  issuance.  As a result,
yields for tax-free money market funds tend to drop, particularly in January.

HOW WILL YOU MANAGE THE FUND OVER THE NEXT SIX MONTHS?

    We'll  continue  to  use a  conservative  approach  to  security  selection,
monitoring the relative  values of one-year notes and  shorter-term  securities.
But because one-year  securities tend to be relatively  unattractive in January,
we don't  expect to buy these  longer-term  securities  until at least  February
unless the outlook for  interest  rates and yields on these  securities  changes
dramatically.

[pie charts]

PORTFOLIO COMPOSITION BY CREDIT RATING (as of 11/30/97)
SP1+               75%
SP1                25%


PORTFOLIO COMPOSITION BY CREDIT RATING (as of 5/31/97)
SP1+               78%
SP1                22%


SEMIANNUAL REPORT                                  MANAGEMENT Q & A       5


<TABLE>
<CAPTION>
                            SCHEDULE OF INVESTMENTS

NOVEMBER 30, 1997 (UNAUDITED)


Principal Amount                                                            Value
- --------------------------------------------------------------------------------------

SHORT-TERM MUNICIPAL SECURITIES

ALASKA--0.7%

<S>             <C>                                                 <C>
                $1,345,000  Anchorage GO, Series 1997 A,
                                4.50%, 12/1/97 (FGIC)(1)             $    1,352,599
                                                                   ---------------------

ARKANSAS--1.6%

                 3,000,000  Pine Bluff Industrial Development Rev., (Camden
                                Wire Co., Inc.), VRDN, 4.00%, 12/4/97 (LOC:
                                Texas Commerce Bank, N. A.)               3,000,000
                                                                   ---------------------

CALIFORNIA--5.1%

                 5,575,000  California Rev. Anticipation Notes,
                                Series 1997 A, 4.50%, 6/30/98(2)          5,595,266

                 1,715,000  Richmond Joint Powers Financing
                                Auth. Port Term Lease Rev.,
                                VRDN, 3.85%, 12/1/97 (LOC:
                                Union Bank of California, N.A.)           1,715,000

                 2,400,000  Sacramento County Housing Auth.
                                Multi-Family Housing Rev., Series
                                1996 C, (River Terrace
                                Apartments), VRDN, 4.20%,
                                12/3/97 (LOC: Dai-Ichi Kangyo
                                Bank, LTD.)                               2,400,000
                                                                   ---------------------

                                                                          9,710,266
                                                                   ---------------------

COLORADO--1.8%

                 3,500,000  Denver Multi-Family Housing Rev., Series 1989 A,
                                (Cottonwood Creek Project), VRDN, 4.30%, 12/2/97
                                (LOC: GE Capital
                                Corp.)                                    3,500,000
                                                                   ---------------------

DELAWARE--1.3%

                 2,500,000  Delaware Economic Development
                                Auth. Industrial Rev.,
                                Series 1997 C, VRDN, 4.00%,
                                12/3/97 (LOC: Canadian
                                Imperial Bank of Commerce)                2,500,000
                                                                   ---------------------

DISTRICT OF COLUMBIA--1.1%

                 2,000,000  District of Columbia Rev., (American University
                                Issue), VRDN, 4.05%, 12/3/97, (LOC:
                                National Westminster Bank PLC)            2,000,000
                                                                   ---------------------


Principal Amount                                                            Value
- --------------------------------------------------------------------------------------

FLORIDA--19.8%

                $4,000,000  Alachua County Industrial
                                Development Rev., (Florida Rock
                                Industries Income Project), VRDN,
                                4.00%, 12/4/97 (LOC: Bank of
                                America N.T. & S.A.)                 $    4,000,000

                 1,000,000  Brevard County Housing Finance
                                Auth. Multi-Family Housing Rev.,
                                (Palm Place Project), VRDN,
                                3.85%, 12/3/97 (LOC: Chase
                                Manhattan Bank)                           1,000,000

                 1,000,000  Broward County Housing Finance
                                Auth. Multi-Family Housing Rev.,
                                (Margate Project), VRDN, 3.85%,
                                12/3/97 (LOC: Chase
                                Manhattan Bank)                           1,000,000

                 6,200,000  Broward County Housing Finance
                                Auth. Multi-Family Housing Rev.,
                                Series 1990 A, (Palmaire-Oxford),
                                VRDN, 4.20%, 12/3/97
                                (SBBPA: Continental Casualty
                                Co.)                                      6,200,000

                 1,655,000  Dade County Housing Auth. Single
                                Family Mortgage Rev., Series
                                1997 C, 4.05%, 2/1/98                     1,655,000

                 3,000,000  Florida Housing Finance Agency
                                Multi-Family Housing Rev.,
                                (Carlton), VRDN, 4.05%,
                                12/3/97 (LOC: Kredietbank
                                N.V.)                                     3,000,000

                 3,000,000  Florida Housing Finance Agency Multi-Family
                                Housing Rev., (Country Club Apartments), VRDN,
                                4.10%,12/1/97 (LOC:
                                Northern Trust Company)                   3,000,000

                 3,790,000  Florida Housing Finance Agency
                                Multi-Family Housing Rev., Series
                                1989 E, VRDN, 4.15%,
                                12/3/97 (LOC: Comerica Bank)              3,790,000

                 5,600,000  Florida Housing Finance Agency
                                Multi-Family Housing Rev., Series
                                1990 B, (Belville-Oxford), VRDN,
                                4.20%, 12/3/97 (SBBPA:
                                Continental Casualty Co.)                 5,600,000

                 1,000,000  Jacksonville Electric Auth. Rev.,
                                VRDN, 4.00%, 12/3/97
                                (Liquidity: Societe Generale)             1,000,000

See Notes to Financial Statements


6      SCHEDULE OF INVESTMENTS                AMERICAN CENTURY INVESTMENTS


                            SCHEDULE OF INVESTMENTS

NOVEMBER 30, 1997 (UNAUDITED)


Principal Amount                                                            Value
- --------------------------------------------------------------------------------------

                $1,000,000  Marion County Housing Finance
                                Auth. Multi-Family Housing Rev.,
                                Series 1985 F, (Paddock Place
                                Project), VRDN, 3.90%,
                                12/4/97 (LOC: Suntrust Bank,
                                Atlanta)                             $    1,000,000

                 2,000,000  Pasco County School Board
                                Certificates of Participation,
                                VRDN, 3.90%, 12/4/97
                                (AMBAC, SBBPA: Landesbank
                                Hessen-Thuringen Girozentrale)            2,000,000

                 2,000,000  Pinnellas County Health Facilities
                                Auth. Rev., VRDN, 3.85%,
                                12/1/97 (LOC: Chase
                                Manhattan Bank)                           2,000,000

                 2,000,000  Port St. Lucie Utility Rev., VRDN,
                                4.10%, 12/4/97 (MBIA,
                                SBBPA: Merrill Lynch)                     2,000,000

                   500,000  Tampa Sports Auth. Rev., (Trust
                                Receipt), VRDN, 3.95%,
                                12/1/97 (MBIA, SBBPA:
                                Societe Generale)                           500,000
                                                                   ---------------------

                                                                         37,745,000
                                                                   ---------------------

GEORGIA--2.5%

                 3,000,000  Burke County Development
                                Pollution Control Rev., Series
                                1997 B, (Oglethorpe Power
                                Corp.), 3.80%, 5/28/98
                                (AMBAC)(2)                                3,000,000

                 1,800,000  Cobb County Multi-Family Housing
                                Rev., (Terrell Mill), VRDN, 4.05%,
                                12/3/97 (LOC: GE Capital
                                Corp.)(3)                                 1,800,000
                                                                   ---------------------

                                                                          4,800,000
                                                                   ---------------------

HAWAII--1.4%

                 2,600,000  Hawaii State Housing Finance and Development
                                Corporation Rev.,(Affordable Rental Housing),
                                VRDN, 3.90%, 12/3/97 (LOC:
                                Banque Nationale De Paris S.A.)           2,600,000
                                                                   ---------------------

ILLINOIS--9.6%

                 1,625,000  Bartlett Multi-Family Housing Rev.,
                                Series 1995 A, (Bartlett Square
                                Apartments), VRDN, 3.95%,
                                12/4/97 (LOC: LaSalle National
                                Bank)                                     1,625,000


Principal Amount                                                            Value
- --------------------------------------------------------------------------------------

                $2,900,000  Galesburg Rev., (Knox College
                                Project), VRDN, 3.90%,
                                12/4/97 (LOC: LaSalle National
                                Bank)                                $    2,900,000

                 2,140,000  Hoffman Estates Tax Increment
                                Rev., (Economic Development
                                Project), 4.50%, 11/15/98
                                (AMBAC)                                   2,150,858

                   720,000  Illinois Health Facility Auth. Rev.,
                                (Sherman Health Systems),
                                3.90%, 8/1/98 (AMBAC)                       720,000

                 2,000,000  Illinois Health Facility Auth. Rev.,
                                Series 1996 B, (Franciscan
                                Eldercare), VRDN, 3.95%,
                                12/3/97 (LOC: ABN Amro
                                Bank N.V.)                                2,000,000

                 2,435,000  Illinois Industrial Development Rev.,
                                (Continental/Midland Project),
                                VRDN, 4.15%, 12/3/97 (LOC:
                                LaSalle National Bank)                    2,435,000

                 2,000,000  McCook Village Rev., Series 1996 B, (St. Andrew
                                Society), VRDN, 3.90%, 12/4/97 (LOC:
                                Northern Trust Company)                   2,000,000

                 4,375,000  Springfield Airport Auth. Rev.,
                                (Allied Signal Project), VRDN,
                                4.25%, 12/3/97 (Corporate
                                Guarantee: Allied Signal, Inc.)           4,375,000
                                                                   ---------------------

                                                                         18,205,858
                                                                   ---------------------

INDIANA--2.9%

                 1,155,000  Central High School Building Corp.
                                Industrial Rev., 4.25%, 8/1/98
                                (AMBAC)                                   1,157,194

                 1,000,000  Gary Industrial Development Rev.,
                                (Tinplate Partners International,
                                Inc.), VRDN, 4.10%, 12/4/97
                                (LOC: LaSalle National Bank)              1,000,000

                 1,000,000  Huntington Economic Development
                                Rev., (Allied Signal Inc. Project),
                                VRDN, 4.00%, 12/3/97
                                (Corporate Guarantee: Allied
                                Signal Inc.)                              1,000,000

                   940,000  Indiana Health Facilities Financing
                                Auth. Hospital Rev., Series 1997 A,
                                (Sisters of St. Francis Health),
                                5.00%, 11/1/98 (MBIA)(1)                    949,099

                   455,000  Noblesville High School Building
                                Corp. Industrial Rev., 3.90%,
                                7/5/98 (AMBAC)                              455,000

See Notes to Financial Statements


     SEMIANNUAL REPORT                           SCHEDULE OF INVESTMENTS       7


                            SCHEDULE OF INVESTMENTS

NOVEMBER 30, 1997 (UNAUDITED)


Principal Amount                                                            Value
- --------------------------------------------------------------------------------------

                $  960,000  Vincennes University Rev., Series
                                1997 E, 3.95%, 12/1/98
                                (AMBAC)(1)                          $       960,000
                                                                   ---------------------

                                                                          5,521,293
                                                                   ---------------------

KANSAS--0.9%

                 1,620,000  Wichita Water & Sewer Utility Rev.,
                                6.50%, 10/1/98 (FGIC)                     1,654,105
                                                                   ---------------------

KENTUCKY--5.1%

                 1,320,000  Kentucky Housing Corp. Rev.,
                                Series 1997 D, 4.00%,
                                12/31/97 (GIC: Bayerische
                                Landesbank Girozentrale)                  1,320,000

                 6,000,000  Kentucky State Turnpike Auth.
                                Resource Recovery Road
                                Certificates of Participation,
                                VRDN, 4.10%, 12/3/97 (FSA,
                                SBBPA: Commerzbank A.G.)                  6,000,000

                 2,400,000  Mayfield Multi-City Lease Rev., VRDN, 4.15%,
                                12/3/97 (LOC:
                                PNC Bank)                                 2,400,000
                                                                   ---------------------

                                                                          9,720,000
                                                                   ---------------------

LOUISIANA--1.1%

                 2,000,000  Calcasieu Parish Sales Tax Rev.,
                                (District No. 4-A Sales and Use
                                Tax), VRDN, 3.85%, 12/4/97
                                (LOC: National Westminster
                                Bank PLC)                                 2,000,000
                                                                   ---------------------

MICHIGAN--2.6%

                 5,000,000  Michigan Strategic Fund Solid
                                Waste Disposal Rev., (Grayling
                                Generating Project), VRDN,
                                4.00%, 12/3/97 (LOC: Barclays
                                Bank PLC)                                 5,000,000
                                                                   ---------------------

MISSOURI--3.5%

                 2,500,000  Fenton Industrial Development
                                Auth. Rev., (Clayton Corp.
                                Project), VRDN, 4.40%,
                                12/4/97 (LOC: Commerce
                                Bank, N. A.)                              2,500,000

                 3,010,000  Missouri Industrial Development
                                Board Rev., VRDN, 4.30%,
                                12/3/97 (LOC: Dai-Ichi Kangyo
                                Bank, Ltd. and Industrial Bank of
                                Japan)                                    3,010,000


Principal Amount                                                            Value
- --------------------------------------------------------------------------------------

                $1,155,000  St. Charles Public Facilities Auth.
                                Leasehold Rev., 4.25%, 2/1/98
                                (MBIA)                               $    1,155,641
                                                                   ---------------------

                                                                          6,665,641
                                                                   ---------------------

NEVADA--1.2%

                   800,000  Clark County Industrial Development
                                Rev., Series 1995 A, (Nevada
                                Power), VRDN, 4.15%, 12/3/97
                                (LOC: Barclays Bank PLC)                    800,000

                 1,500,000  Clark County Industrial Development
                                Rev., Series 1995 C, (Nevada
                                Power), VRDN, 4.05%, 12/3/97
                                (LOC: Barclays Bank PLC)                  1,500,000
                                                                   ---------------------

                                                                          2,300,000
                                                                   ---------------------

NEW MEXICO--4.8%

                 7,200,000  Farmington Pollution Control Rev.,
                                Series 1997 A, (San Juan
                                Project), VRDN, 4.15%,
                                12/3/97 (LOC: Bank of America)            7,200,000

                 2,000,000  New Mexico Mortgage Financing
                                Auth. Rev., Issue 2, 3.90%,
                                10/15/98 (GIC: FGIC)                      2,000,000
                                                                   ---------------------

                                                                          9,200,000
                                                                   ---------------------

NEW YORK--2.6%

                 5,000,000  New York State Energy Research
                                and Development Auth. Pollution
                                Control Rev., Series 1997 B,
                                (Rochester Gas & Electric Corp.),
                                VRDN, 4.00%, 12/3/97 (MBIA,
                                SBBPA: Credit Suisse First
                                Boston)                                   5,000,000
                                                                   ---------------------

OHIO--3.8%

                 3,255,000  Ohio State Building Auth. Rev.,
                                Series 1997 A, (Adult Correctional
                                Building), 4.50%, 4/1/98(2)               3,259,334

                 4,000,000  Ohio State Water Air Quality
                                Pollution Control Rev.
                                Commercial Paper, Series
                                1988 B, 3.75%, 12/16/97
                                (FGIC, LOC: General Electric
                                Capital Corp. Liquidity)                  4,000,000
                                                                   ---------------------

                                                                          7,259,334
                                                                   ---------------------

See Notes to Financial Statements


8      SCHEDULE OF INVESTMENTS                AMERICAN CENTURY INVESTMENTS


                            SCHEDULE OF INVESTMENTS

NOVEMBER 30, 1997 (UNAUDITED)


Principal Amount                                                            Value
- --------------------------------------------------------------------------------------

OREGON--0.5%

                $1,000,000  Oregon State GO Commercial
                                Paper, (Veterans Welfare), 4.05%,
                                2/2/98                               $    1,000,000
                                                                   ---------------------

PENNSYLVANIA--6.9%

                 6,000,000  Dauphin County General Auth. Rev.,
                                Series 1997 A, VRDN, 4.00%,
                                12/3/97 (FSA, SBBPA: Credit
                                Suisse First Boston)                      6,000,000

                 7,200,000  Emmaus General Auth. Rev., VRDN,
                                3.95%, 12/3/97 (LOC:
                                Bayerische Landesbank
                                Girozentrale)                             7,200,000
                                                                   ---------------------

                                                                         13,200,000
                                                                   ---------------------

SOUTH CAROLINA--2.5%

                 4,725,000  Berkeley County Pollution Control
                                Rev., VRDN, 3.90%, 12/4/97
                                (LOC: Royal Bank of Canada)               4,725,000
                                                                   ---------------------

TENNESSEE--1.1%

                 2,000,000  Chattanooga Industrial
                                Development Rev., (Market
                                Street Limited Project), VRDN,
                                4.00%, 12/3/97 (LOC: Credit
                                Suisse First Boston, Inc.)                2,000,000
                                                                   ---------------------

TEXAS--10.0%

                   575,000  Arlington Hospital Auth. Rev.,
                                (Arlington Memorial Hospital),
                                5.50%, 12/1/97 (FSA)                        575,000

                   500,000  Dallas GO Commercial Paper,
                                (Dallas, Denton and Collin Co.),
                                4.20%, 2/15/98                              500,000

                 1,475,000  Greenville Electric Utility System
                                Rev., 4.25%, 2/15/98 (FSA)(1)             1,476,166

                   780,000  Houston Water and Sewer System
                                Rev., 8.00%, 12/1/97,
                                Prerefunded at 102% of Par(4)               796,234

                 4,495,000  Midland County Hospital District
                                Rev., VRDN, 4.10%, 12/4/97
                                (AMBAC, SBBPA: Merrill Lynch)             4,495,000

                 2,100,000  Tarrant County Housing Finance
                                Rev., (Windcastle Project), VRDN,
                                4.05%, 12/3/97 (LOC: Swiss
                                Bank Corporation)                         2,100,000


Principal Amount                                                            Value
- --------------------------------------------------------------------------------------

                $4,150,000  Texas Higher Education Auth. Rev.,
                                Series 1985 B, VRDN, 4.00%,
                                12/3/97 (FGIC)                       $    4,150,000

                 5,000,000  Texas Tax and Rev. Anticipation
                                Notes, 4.75%, 8/31/98(2)                  5,032,231
                                                                   ---------------------

                                                                         19,124,631
                                                                   ---------------------

WASHINGTON--4.7%

                 1,800,000  Pierce County Economic Development Corporate
                                Rev., (K & M Holdings II Project), VRDN, 4.15%,
                                12/3/97 (LOC:
                                Wells Fargo Bank, N. A.)                  1,800,000

                 6,600,000  Washington State Housing Finance
                                Commission Multi-Family
                                Mortgage Rev., (Mill Plain
                                Crossing Project), VRDN, 4.00%,
                                12/2/97 (LOC: Harris Trust &
                                Savings Bank)                             6,600,000

                   485,000  Washington State Housing Finance
                                Commission Rev., Series 1997 1A,
                                4.00%, 4/1/98 (GIC: FGIC)                   485,000
                                                                   ---------------------

                                                                          8,885,000
                                                                   ---------------------

WISCONSIN--0.9%

                 1,800,000  Pleasant Prairie Industrial
                                Development Rev., (Muskie
                                Enterprises), VRDN, 4.05%,
                                12/4/97 (LOC: Bank of
                                Montreal)                                 1,800,000
                                                                   ---------------------

TOTAL INVESTMENT SECURITIES--100.0%                                    $190,468,727
                                                                   =====================
</TABLE>

See Notes to Financial Statements


SEMIANNUAL REPORT                           SCHEDULE OF INVESTMENTS       9


                            SCHEDULE OF INVESTMENTS

NOTES TO SCHEDULE OF INVESTMENTS

AMBAC = AMBAC Indemnity Corporation

FGIC = Financial Guaranty Insurance Co.

FSA = Financial Security Assurance

GIC = Guaranteed Investment Contract

GO = General Obligation

LOC = Letter of Credit

MBIA = MBIA Insurance Company

SBBPA = Standby Bond Purchase Agreement

VRDN  = Variable Rate Demand Note.  Interest reset date is indicated and used in
      calculating  the  weighted  average  portfolio  maturity.  Rate  shown  is
      effective November 30, 1997.

(1)  When-issued security.

(2)  Security, or portion thereof, has been segregated at the custodian bank for
     a when-issued security.

(3)  Security was purchased  under Rule 144A of the Securities Act of 1933 or is
     otherwise  restricted as to resale and, unless  registered under the Act or
     exempted  from  registration,  may only be sold to qualified  institutional
     investors.  The aggregate  value of  restricted  securities at November 30,
     1997, was $1,800,000, which represented 0.9% of net assets.

(4)  Escrowed to maturity in U.S. Government Securities.

See Notes to Financial Statements


10      SCHEDULE OF INVESTMENTS                AMERICAN CENTURY INVESTMENTS


                      STATEMENT OF ASSETS AND LIABILITIES

NOVEMBER 30, 1997 (UNAUDITED)

ASSETS

Investment securities, at value
  (amortized cost and cost for
  federal income tax purposes) .................... $190,468,727

Cash ..............................................   4,560,924

Receivable for investments sold ...................   3,900,000

Interest receivable ...............................    918,825
                                                   --------------
                                                     199,848,476
                                                   --------------
LIABILITIES

Disbursements in excess of
  demand deposit cash .............................    227,151

Payable for investments purchased .................   4,755,372

Payable for capital shares
  redeemed ........................................    12,562

Dividends payable .................................    44,310
                                                   --------------
                                                      5,039,395
                                                   --------------
Net Assets ........................................ $194,809,081
                                                   ==============
CAPITAL SHARES

Outstanding (Unlimited number
  of shares authorized) ...........................  194,809,081
                                                   ==============
Net Asset Value Per Share .........................     $1.00
                                                   ==============
NET ASSETS CONSIST OF:

Capital paid in ................................... $194,809,081
                                                   ==============
See Notes to Financial Statements


SEMIANNUAL REPORT                STATEMENT OF ASSETS AND LIABILITIES      11


                            STATEMENT OF OPERATIONS

FOR THE SIX MONTHS ENDED NOVEMBER 30, 1997 (UNAUDITED)

INVESTMENT INCOME

Income:

Interest .........................................   $2,119,414
                                                   --------------
Expenses (Note 2):

Investment advisory fees .........................      267,454

Administrative fees ..............................      13,717

Printing and postage .............................      11,827

Registration and filing fees .....................      11,103

Transfer agency fees .............................       9,971

Custodian fees ...................................       3,274

Auditing and legal fees ..........................       3,057

Trustees' fees and expenses ......................       1,053

Other operating expenses .........................       2,094
                                                   --------------
  Total expenses .................................     323,550

Amount waived ....................................    (225,014)
                                                   --------------
  Net expenses ...................................     98,536
                                                   --------------
Net investment income ............................   $2,020,878
                                                   ==============
See Notes to Financial Statements


12      STATEMENT OF OPERATIONS                AMERICAN CENTURY INVESTMENTS


                      STATEMENTS OF CHANGES IN NET ASSETS

SIX MONTHS ENDED NOVEMBER 30, 1997 (UNAUDITED)

AND YEAR ENDED MAY 31, 1997

                                                 November 30,         May 31,
Increase (Decrease) in Net Assets                    1997              1997

OPERATIONS

Net investment income ....................     $   2,020,878      $   2,620,733
                                               -------------      -------------
DISTRIBUTIONS TO SHAREHOLDERS

From net investment income ...............        (2,020,878)        (2,620,733)
                                               -------------      -------------
CAPITAL SHARE TRANSACTIONS

Proceeds from shares sold ................       173,821,973         79,662,054

Proceeds from reinvestment
  of distributions .......................         1,858,011          2,479,220

Payments for shares redeemed .............       (66,601,295)       (87,528,514)
                                               -------------      -------------
Net increase (decrease) in net
  assets from capital share transactions .       109,078,689         (5,387,240)
                                               -------------      -------------
Net increase (decrease) in net assets ....       109,078,689         (5,387,240)
                                               =============      =============
NET ASSETS

Beginning of period ......................        85,730,392         91,117,632
                                               -------------      -------------
End of period ............................     $ 194,809,081      $  85,730,392

TRANSACTIONS IN SHARES
OF THE FUND

Sold .....................................       173,821,973         79,662,054

Issued in reinvestment of distributions ..         1,858,011          2,479,220

Redeemed .................................       (66,601,295)       (87,528,514)
                                               -------------      -------------
Net increase (decrease) ..................       109,078,689         (5,387,240)
                                               =============      =============
See Notes to Financial Statements


SEMIANNUAL REPORT               STATEMENTS OF CHANGES IN NET ASSETS       13


                         NOTES TO FINANCIAL STATEMENTS

NOVEMBER 30, 1997 (UNAUDITED)

1. ORGANIZATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES

    ORGANIZATION--American  Century  Municipal Trust (the Trust),  is registered
under the Investment  Company Act of 1940 as an open-end  management  investment
company. American Century - Benham Tax-Free Money Market Fund (the Fund), is one
of the seven funds issued by the Trust.  The Fund is diversified  under the 1940
Act.  Its  objective  is to seek as high a level of current  income  exempt from
federal  income taxes as is consistent  with prudent  investment  management and
conservation  of  shareholders'  capital by investing  primarily  in  short-term
municipal  obligations.  The Fund may  concentrate  its  investments  in certain
states and  therefore  may have more  exposure to credit  risk  related to those
states than funds that have broader geographical diversification.  The following
significant  accounting  policies,  related to the Fund, are in accordance  with
accounting policies generally accepted in the investment company industry.

    SECURITY  VALUATIONS--Portfolio  securities  are valued at  amortized  cost,
which  approximates  current  market  value.  When  valuations  are not  readily
available,  securities are valued at fair value as determined in accordance with
procedures adopted by the Board of Trustees.

    SECURITY  TRANSACTIONS--Security  transactions are accounted for on the date
purchased  or  sold.  Net  realized  gains  and  losses  are  determined  on the
identified cost basis, which is also used for federal income tax purposes.

    INVESTMENT  INCOME--Interest  income is recorded  on the  accrual  basis and
includes  accretion of discounts  and  amortization  of premiums.  Discounts and
premiums are accrued daily on a straight-line basis.

    INCOME  TAX  STATUS--It  is the  policy  of the Fund to  distribute  all net
investment  income  and  net  realized  capital  gains  to  shareholders  and to
otherwise qualify as a regulated  investment company under the provisions of the
Internal  Revenue Code.  Accordingly,  no provision has been made for federal or
state taxes.

    DISTRIBUTIONS TO SHAREHOLDERS--Distributions  from net investment income are
declared and credited daily and distributed monthly. The Fund does not expect to
realize any long-term capital gains, and accordingly, does not expect to pay any
capital gain distributions.

    The  character  of  distributions  made during the year from net  investment
income or net realized gains may differ from their ultimate characterization for
federal income tax purposes due to differences in the  recognition of income and
expense items for financial reporting and tax purposes.

    USE OF ESTIMATES--The preparation of financial statements in conformity with
generally accepted  accounting  principles requires management to make estimates
and assumptions  that affect the reported  amounts of assets and liabilities and
disclosure of  contingent  assets and  liabilities  at the date of the financial
statements  and the reported  amounts of increases  and  decreases in net assets
from  operations  during the  period.  Actual  results  could  differ from these
estimates.


14      NOTES TO FINANCIAL STATEMENTS          AMERICAN CENTURY INVESTMENTS


                         NOTES TO FINANCIAL STATEMENTS

NOVEMBER 30, 1997 (UNAUDITED)

2. TRANSACTIONS WITH RELATED PARTIES

    The  shareholders  of the Fund  approved  a new  management  agreement  with
American Century Investment Management,  Inc. (ACIM) on July 30, 1997, effective
August 1, 1997,  which  replaced  the  existing  contracts  between the Fund and
Benham Management  Corporation and American Century Services  Corporation (ACSC)
for advisory,  administrative  and transfer agency services.  Expenses  excluded
from the agreement are brokerage, taxes, portfolio insurance, interest, fees and
expenses of the Trustees who are not considered  "interested persons" as defined
in the Investment Company Act of 1940 (including counsel fees) and extraordinary
expenses.  Under the agreement,  ACIM will provide all services  required by the
Fund in exchange for one unified  management  fee. The annual rate at which this
fee is assessed is determined  monthly in a two-step process:  First, a fee rate
schedule  is applied to the assets of all of the funds in the Fund's  investment
category which are managed by ACIM (the "Investment  Category Fee"). The overall
investment objective of the Fund determines its Investment  Category.  The three
investment  categories  are:  the  Money  Market  Fund  Category,  the Bond Fund
Category, and the Equity Fund Category. The Fund is included in the Money Market
Fund Category.  Second, a separate fee rate schedule is applied to the assets of
all of the funds managed by ACIM (the "Complex  Fee").  The Investment  Category
Fee and the Complex Fee are then added to determine the unified  management  fee
rate.  The  management  fee is paid  monthly by the Fund based on its  aggregate
average  daily net assets  during the previous  month  multiplied by the monthly
management  fee rate. The  annualized  Investment  Category Fee schedule for the
Fund is as follows:

     0.2700% of the first $1 billion 
     0.2270% of the next $1 billion 
     0.1860% of the next $3 billion 
     0.1690% of the next $5 billion 
     0.1580% of the next $15 billion 
     0.1575% of the next $25 billion
     0.1570% of the average daily net assets over $50 billion

    The annualized Complex Fee schedule is as follows:

     0.3100% of the first $2.5 billion 
     0.3000% of the next $7.5 billion 
     0.2985% of the next $15 billion 
     0.2970% of the next $25 billion 
     0.2960% of the next $50 billion 
     0.2950% of the next $100 billion 
     0.2940% of the next $100 billion 
     0.2930% of the next $200 billion 
     0.2920% of the next $250 billion
     0.2910% of the next $500 billion
     0.2900% of the average daily net assets over $1,250 billion

    Effective August 1, 1997, ACIM has agreed to waive its entire management fee
and absorb all other expenses until August 1, 1998.  Management fees of $199,575
were incurred under the new management  agreement and are included in Investment
Advisory Fees and Amount Waived in the Statement of  Operations.  Total expenses
and the annualized ratio of operating expenses to average net assets,  under the
previous agreement,  for the two months ended July 31, 1997 were $98,536, net of
the amount waived by Benham  Management  Corporation of $25,439.  The annualized
ratio of operating expenses to average net assets, net of the amount waived, for
the same period was 0.67%.

    Certain  officers  and  trustees  of the  Trust  are  also  officers  and/or
directors,  and,  as a  group,  controlling  stockholders  of  American  Century
Companies,  Inc. (ACC), the parent of the Trust's investment manager,  ACIM, the
Trust's transfer agent, ACSC, and the registered broker-dealer, American Century
Investment Services, Inc.


SEMIANNUAL REPORT                     NOTES TO FINANCIAL STATEMENTS       15

<TABLE>
<CAPTION>
                             FINANCIAL HIGHLIGHTS

    For a Share Outstanding Throughout the Years Ended May 31 (except as noted)

                                  1997(1)         1997           1996            1995           1994           1993

PER-SHARE DATA

Net Asset Value,
<S>                                <C>            <C>            <C>             <C>            <C>            <C>  
Beginning of Period .............  $1.00          $1.00          $1.00           $1.00          $1.00          $1.00
                                 ---------      --------       ---------      ---------      ----------     ----------
Income From
Investment Operations

  Net Investment Income .........  0.02           0.03           0.03            0.03           0.02           0.02
                                 ---------      --------       ---------      ---------      ----------     ----------
Distributions

  From Net Investment Income .... (0.02)         (0.03)         (0.03)          (0.03)         (0.02)         (0.02)
                                 ---------      --------       ---------      ---------      ----------     ----------
Net Asset Value, End of Period ..  $1.00          $1.00          $1.00           $1.00          $1.00          $1.00
                                 =========      ========       =========      =========      ==========     ==========
  Total Return(2) ...............  1.82%          2.98%          3.19%           2.95%          1.92%          2.12%

RATIOS/SUPPLEMENTAL DATA

Ratio of Operating Expenses
to Average Net Assets ...........0.18%(3)         0.67%          0.65%           0.66%          0.67%          0.68%

Ratio of Net Investment
Income to Average
Net Assets ......................3.67%(3)         2.93%          3.12%           2.88%          1.89%          2.10%

Net Assets, End
of Period (in thousands) ........$194,809        $85,730        $91,118         $92,034       $109,818       $109,875
</TABLE>
- ----------
(1)  Six months ended November 30, 1997 (unaudited).

(2)  Total  return   assumes   reinvestment   of  dividends  and  capital  gains
     distributions, if any. Total returns for periods less than one year are not
     annualized.

(3)  Annualized.  ACIM has voluntarily waived its management fee until August 1,
     1998. In absence of the waiver,  the ratio of operating expenses to average
     net assets would have been 0.59% and the ratio of net investment  income to
     average net assets would have been 3.27%.

See Notes to Financial Statements


16      FINANCIAL HIGHLIGHTS                   AMERICAN CENTURY INVESTMENTS


                             PROXY VOTING RESULTS

    An annual meeting of shareholders  was held on July 30, 1997, to vote on the
following  proposals.  All of the  proposals  received the required  majority of
votes and were adopted.

    A summary of voting results is listed below each proposal.

PROPOSAL 1:

    To vote on the selection by the Board of Trustees of Coopers & Lybrand
L.L.P. as independent auditors for the Trust.

    For:                                       49,222,232
    Against:                                    2,646,331
    Abstain:                                     321,231


PROPOSAL 2:

    To vote on the  approval of a Management  Agreement  with  American  Century
Investment Management, Inc.

    For:                                       48,548,777
    Against:                                    3,168,105
    Abstain:                                     472,912


PROPOSAL 3:

    To vote on the adoption of standardized investment limitations.

*  Eliminate the fundamental investment limitation concerning diversification of
   investments.

    For:                                       45,057,390
    Against:                                    6,079,148
    Abstain:                                    1,053,256

*  Amend the fundamental investment limitation concerning the issuance of senior
    securities.

    For:                                       44,985,317
    Against:                                    6,151,221
    Abstain:                                    1,053,256

*  Amend the fundamental investment limitation concerning borrowing.

    For:                                       44,949,793
    Against:                                    6,186,745
    Abstain:                                    1,053,256

*  Amend the fundamental investment limitation concerning lending.

    For:                                       44,938,973

    Against:                                    6,197,565

    Abstain:                                    1,053,256

*  Eliminate the fundamental investment limitation regarding investments in
   illiquid securities.

    For:                                       46,367,051
    Against:                                    4,769,487
    Abstain:                                    1,053,256

*  Eliminate the fundamental limitation concerning investment in other
   investment companies.

    For:                                       44,834,302
    Against:                                    6,302,236
    Abstain:                                    1,053,256

*  Amend the fundamental investment limitation concerning investments in real
    estate.

    For:                                       44,742,211
    Against:                                    6,394,327
    Abstain:                                    1,053,256

*  Amend the fundamental investment limitation concerning underwriting.

    For:                                       44,681,197
    Against:                                    6,455,341
    Abstain:                                    1,053,256

*  Amend the fundamental investment limitation concerning commodities.

    For:                                       44,880,646
    Against:                                    6,255,892
    Abstain:                                    1,053,256


SEMIANNUAL REPORT                              PROXY VOTING RESULTS       17


                             PROXY VOTING RESULTS

*  Eliminate the fundamental limitation concerning short sales.

    For:                                       44,834,064
    Against:                                    6,302,474
    Abstain:                                    1,053,256

*  Eliminate the fundamental investment limitation concerning margin purchases
   of securities.

    For:                                       46,240,501
    Against:                                    4,896,037
    Abstain:                                    1,053,256

*  Eliminate the fundamental investment limitation concerning warrants.

    For:                                       44,634,615
    Against:                                    6,501,923
    Abstain:                                    1,053,256

*   Eliminate the fundamental  investment limitation  concerning  investments in
    oil, gas and mineral exploration development programs.

    For:                                       44,844,560
    Against:                                    6,291,978
    Abstain:                                    1,053,256

*   Eliminate the fundamental  investment  limitations concerning investments in
    securities owned by officers and directors.

    For:                                       44,845,122
    Against:                                    6,291,416
    Abstain:                                    1,053,256


18      PROXY VOTING RESULTS                   AMERICAN CENTURY INVESTMENTS


                                     NOTES


SEMIANNUAL REPORT                                             NOTES       19


                            BACKGROUND INFORMATION

INVESTMENT PHILOSOPHY & POLICIES

    The Benham Group  offers 38  fixed-income  funds,  ranging from money market
funds to long-term bond funds and including  both taxable and tax-exempt  funds.
Each fund is  managed  to  provide  a "pure  play" on a  specific  sector of the
fixed-income market. To ensure adherence to this principle,  the basic structure
of each fund's  portfolio  is tied to a specific  market  index.  Fund  managers
attempt  to add  value by making  modest  portfolio  adjustments  based on their
analysis of  prevailing  market  conditions.  Investment  decisions  are made by
management teams, which meet regularly to discuss market analysis and investment
strategies.

    In addition to these principles, each fund has its own investment policies:

    TAX-FREE MONEY MARKET is a money market fund that seeks to provide  interest
income  exempt from federal  income taxes by investing in  short-term  municipal
securities.

    Investments in Tax-Free  Money Market are neither  insured nor guaranteed by
the U.S. government.  Yields will fluctuate,  and there can be no assurance that
the fund will be able to maintain a stable net asset value of $1 per share.

    Investment  income  may be subject to  certain  state and local  taxes,  and
depending on your tax status, may be subject to the federal  alternative minimum
tax. Capital gains are not exempt from federal income tax.

LIPPER RANKINGS

    LIPPER  ANALYTICAL  SERVICES,  INC. is an  independent  mutual fund  ranking
service that groups funds according to their investment objectives. Rankings are
based on  average  annual  returns  for each  fund in a given  category  for the
periods indicated. Rankings are not included for periods less than one year.

    The Lipper category for the fund is:

    TAX-EXEMPT MONEY MARKET FUNDS --funds that intend to maintain a constant net
asset   value   and   invest  in   high-quality   municipal   obligations   with
dollar-weighted average maturities of less than 90 days.

INVESTMENT TEAM LEADERS

 Portfolio Manager                             Bryan Karcher

 Credit Research Manager                       Steven Permut


20      BACKGROUND INFORMATION                 AMERICAN CENTURY INVESTMENTS


                                   GLOSSARY

RETURNS

* TOTAL  RETURN  figures  show the overall  percentage  change in the value of a
hypothetical  investment  in  the  fund  and  assume  that  all  of  the  fund's
distributions are reinvested.

* AVERAGE ANNUAL RETURNS  illustrate the annually  compounded returns that would
have produced the fund's cumulative total returns if the fund's  performance had
been  constant  over the  entire  period.  Average  annual  returns  smooth  out
variations  in a fund's  return;  they are not the same as  fiscal  year-by-year
results.  For  fiscal  year-by-year  returns,  please  refer  to the  "Financial
Highlights" on page 16.

YIELDS

* 7-DAY  CURRENT  YIELD  is  calculated  based  on the  income  generated  by an
investment  in the fund over a seven-day  period and is  expressed  as an annual
percentage rate.

* 7-DAY  EFFECTIVE  YIELD is  calculated  similarly,  although  this  figure  is
slightly  higher than the fund's 7-Day  Current  Yield because of the effects of
compounding. The 7-Day Effective Yield assumes that income earned from the fund'
s investments is reinvested and generating additional income.

*  TAX-EQUIVALENT  YIELDS show the taxable  yields that  investors  in a federal
income tax bracket would have to earn before taxes to equal the fund's  tax-free
yield.

INVESTMENT TERMS

* BASIS POINT--a basis point equals one  one-hundredth of a percentage point (or
0.01%). Therefore, 100 basis points equals one percentage point (or 1%).

* YIELD CURVE--a graphic representation of the relationship between maturity and
yield  for  fixed-income   securities.   Yield  curve  graphs  plot  lengthening
maturities along the horizontal axis and rising yields along the vertical axis.

PORTFOLIO STATISTICS

* NUMBER OF SECURITIES--the  number of different  securities held by a fund on a
given date.

*  WEIGHTED  AVERAGE  MATURITY  (WAM)--a  measurement  of the  sensitivity  of a
fixed-income  portfolio to interest rate changes. WAM indicates the average time
until the securities in the portfolio mature, weighted by dollar amount.

* EXPENSE RATIO--the  operating expenses of the fund,  expressed as a percentage
of average net assets.  Shareholders pay an annual fee to the investment manager
for  investment  advisory  and  management  services.  The expenses and fees are
deducted from fund income, not from each shareholder account. (See Note 2 in the
Notes to Financial Statements.)

TYPES OF MUNICIPAL SECURITIES

* MUNICIPAL COMMERCIAL PAPER (CP)--high-grade  short-term securities backed by a
line of credit from a bank.

* MUNICIPAL NOTES--securities with maturities of two years or less.

*  VARIABLE-RATE  DEMAND NOTES  (VRDNS)--securities  that track market  interest
rates and  stabilize  their  market  values  using  periodic  (daily or  weekly)
interest rate adjustments.


SEMIANNUAL REPORT                                          GLOSSARY       21


[american century logo]
American
Century(reg.sm)

P.O. BOX 419200
KANSAS CITY, MISSOURI
64141-6200

INVESTOR SERVICES:
1-800-345-2021 OR 816-531-5575

AUTOMATED INFORMATION LINE:
1-800-345-8765

TELECOMMUNICATIONS DEVICE FOR THE DEAF:
1-800-634-4113 OR 816-444-3485

FAX: 816-340-7962

INTERNET: WWW.AMERICANCENTURY.COM


AMERICAN CENTURY MUNICIPAL TRUST


INVESTMENT MANAGER

AMERICAN CENTURY INVESTMENT MANAGEMENT, INC.

KANSAS CITY, MISSOURI


THIS  REPORT AND THE  STATEMENTS  IT  CONTAINS  ARE  SUBMITTED  FOR THE  GENERAL
INFORMATION OF OUR  SHAREHOLDERS.  THE REPORT IS NOT AUTHORIZED FOR DISTRIBUTION
TO  PROSPECTIVE  INVESTORS  UNLESS  PRECEDED  OR  ACCOMPANIED  BY  AN  EFFECTIVE
PROSPECTUS.


(c) 1998 AMERICAN CENTURY SERVICES CORPORATION FUNDS DISTRIBUTOR, INC.


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