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                            VAN KAMPEN RESERVE FUND
                        SUPPLEMENT DATED APRIL 28, 2000,
               SUPERCEDING THE SUPPLEMENT DATED JANUARY 11, 2000
                      PROSPECTUS DATED SEPTEMBER 28, 1999

                              VAN KAMPEN PACE FUND
                        SUPPLEMENT DATED APRIL 28, 2000,
               SUPERCEDING THE SUPPLEMENT DATED JANUARY 11, 2000
                       PROSPECTUS DATED OCTOBER 28, 1999

    The Prospectus is hereby supplemented as follows:

    (1) The information on the inside back cover of the Prospectus under the
heading "BOARD OF TRUSTEES AND OFFICERS--BOARD OF TRUSTEES" is hereby amended by
deleting Paul G. Yovovich, effective April 14, 2000, and by deleting and
replacing Richard M. DeMartini* and Don G. Powell* with Mitchell M. Merin* and
Richard F. Powers, III*, effective December 15, 1999.

    (2) The information on the inside back cover of the Prospectus under the
heading "BOARD OF TRUSTEES AND OFFICERS--OFFICERS" is hereby amended by deleting
all information pertaining to Curtis W. Morell* and Tanya M. Loden*, effective
January 31, 2000, Dennis J. McDonnell*, effective March 31, 2000, and by
deleting and replacing Stephen L. Boyd's title of Vice President with Executive
Vice President and Chief Investment Officer and Edward C. Wood, III*, Vice
President, with John H. Zimmermann, III*, Vice President, effective April 17,
2000.

                  RETAIN THIS SUPPLEMENT FOR FUTURE REFERENCE
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                            VAN KAMPEN RESERVE FUND
                     SUPPLEMENT DATED APRIL 28, 2000 TO THE

         STATEMENT OF ADDITIONAL INFORMATION DATED SEPTEMBER 28, 1999,
    SUPERCEDING THE SUPPLEMENTS DATED JANUARY 11, 2000 AND JANUARY 18, 2000

     The Statement of Additional Information is hereby supplemented as follows:

     (1) The section entitled "TRUSTEES AND OFFICERS" is hereby amended by
deleting all information pertaining to Paul G. Yovovich, effective April 14,
2000, and Richard M. DeMartini and Don G. Powell, effective December 15, 1999.

     (2) The section entitled "TRUSTEES AND OFFICERS--TRUSTEES" is hereby
amended, effective December 15, 1999, by adding the following:

                                    
Mitchell M. Merin*...................  President and Chief Operating Officer of asset management of
Two World Trade Center                 Morgan Stanley Dean Witter since December 1998. President
66th Floor                             and Director since April 1997 and Chief Executive Officer
New York, NY 10048                     since June 1998 of Morgan Stanley Dean Witter Advisors Inc.
Date of Birth: 08/13/53                and Morgan Stanley Dean Witter Services Company Inc.
                                       Chairman, Chief Executive Officer and Director of Morgan
                                       Stanley Dean Witter Distributors Inc. since June 1998.
                                       Chairman and Chief Executive Officer since June 1998, and
                                       Director since January 1998, of Morgan Stanley Dean Witter
                                       Trust FSB. Director of various Morgan Stanley Dean Witter
                                       subsidiaries. President of the Morgan Stanley Dean Witter
                                       funds and Discover Brokerage Index Series since May 1999.
                                       Trustee/Director of each of the funds in the Fund Complex,
                                       and Vice President of other investment companies advised by
                                       the Advisers and their affiliates. Previously Chief
                                       Strategic Officer of Morgan Stanley Dean Witter Advisors
                                       Inc. and Morgan Stanley Dean Witter Services Company Inc.
                                       and Executive Vice President of Morgan Stanley Dean Witter
                                       Distributors Inc. April 1997-June 1998, Vice President of
                                       the Morgan Stanley Dean Witter Funds and Discover Brokerage
                                       Index Series May 1997-April 1999, and Executive Vice
                                       President of Dean Witter, Discover & Co.
Richard F. Powers, III*..............  Chairman, President and Chief Executive Officer of Van
1 Parkview Plaza                       Kampen Investments. Chairman, Director and Chief Executive
P.O. Box 5555                          Officer of the Advisers, the Distributor, Van Kampen
Oakbrook Terrace, IL 60181-5555        Advisors Inc. and Van Kampen Management Inc. Director and
Date of Birth: 02/02/46                officer of certain other subsidiaries of Van Kampen
                                       Investments. Trustee/Director and President of each of the
                                       funds in the Fund Complex. Trustee, President and Chairman
                                       of the Board of other investment companies advised by the
                                       Advisers and their affiliates, and Chief Executive Officer
                                       of Van Kampen Exchange Fund. Prior to May 1998, Executive
                                       Vice President and Director of Marketing at Morgan Stanley
                                       Dean Witter and Director of Dean Witter Discover & Co. and
                                       Dean Witter Realty. Prior to 1996, Director of Dean Witter
                                       Reynolds Inc.



     (3) The footnote at the end of the section entitled "TRUSTEES AND
OFFICERS--TRUSTEES" is hereby deleted in its entirety and replaced with the
following:

          * Such trustee is an "interested person" (within the meaning of
     Section 2(a)(19) of the 1940 Act). Mr. Whalen is an interested person of
     each of the funds in the Fund Complex by reason of his firm currently
     acting as legal counsel to each of the Funds in the Fund Complex. Messrs.
     Merin and Powers are interested persons of each of the Funds in the Fund
     Complex and the Advisers by reason of their positions with Morgan Stanley
     Dean Witter or its affiliates.

     (4) The section entitled "TRUSTEES AND OFFICERS--OFFICERS" is hereby
amended by deleting all information pertaining to Weston B. Wetherell, Sara L.
Badler, Jacqueline F. Denter, and James M. Dykas,
   3

effective January 31, 2000, Dennis J. McDonnell, effective March 31, 2000, and
Edward C. Wood, III and Stephen L. Boyd, effective April 17, 2000, and by adding
the following:

                                         
Stephen L. Boyd...........................  Executive Vice President and Chief Investment Officer of
Date of Birth: 11/16/40                     Van Kampen Investments, and President and Chief Operating
Executive Vice President and                Officer of the Advisers. Executive Vice President and
Chief Investment Officer                    Chief Investment Officer of each of the funds in the Fund
                                            Complex and certain other investment companies advised by
                                            the Advisers or their affiliates. Prior to April 2000,
                                            Vice President and Chief Investment Officer of the
                                            Advisers. Prior to October 1998, Vice President and
                                            Senior Portfolio Manager with AIM Capital Management,
                                            Inc. Prior to February 1998, Senior Vice President and
                                            Portfolio Manager of Van Kampen American Capital Asset
                                            Management, Inc., Van Kampen American Capital Investment
                                            Advisory Corp. and Van Kampen American Capital
                                            Management, Inc.
John H. Zimmermann, III...................  Senior Vice President and Director of Van Kampen
Date of Birth: 11/25/57                     Investments, President and Director of the Distributor
Vice President                              and President of Van Kampen Insurance Agency of Illinois
                                            Inc. Vice President of each of the funds in the Fund
                                            Complex. From November 1992 to December 1997, Senior Vice
                                            President of the Distributor.



     (5) The second sentence of the first paragraph immediately following the
section entitled "TRUSTEES AND OFFICERS--OFFICERS" is hereby deleted in its
entirety.

     (6) The footnote to the "CLASS A SHARES SALES CHARGE TABLE" at the end of
the second paragraph in the section entitled "DISTRIBUTION AND SERVICE" is
hereby deleted in its entirety and replaced with the following:

          * No sales charge is payable at the time of purchase on investments of
     $1 million or more, although the Fund may impose a contingent deferred
     sales charge of 1.00% on certain redemptions made within one year of
     purchase. A commission or transaction fee will be paid by the Distributor
     at the time of purchase directly out of the Distributor's assets (and not
     out of the Fund's assets) to authorized dealers who initiate and are
     responsible for purchases of $1 million or more computed on a percentage of
     the dollar value of such shares sold as follows: 1.00% on sales to $2
     million, plus 0.80% on the next $1 million and 0.50% on the excess over $3
     million. For single purchases of $20 million or more by an individual
     retail investor the Distributor will pay, at the time of purchase and
     directly out of the Distributor's assets (and not out of the Fund's
     assets), a commission or transaction fee of 1.00% to authorized dealers who
     initiate and are responsible for such purchases. The commission or
     transaction fee of 1.00% will be computed on a percentage of the dollar
     value of such shares sold.