1
                       SECURITIES AND EXCHANGE COMMISSION
                              WASHINGTON, DC 20549

                                   SCHEDULE TO

        TENDER OFFER STATEMENT UNDER SECTION 14(d)(1) OR 13(e)(1) OF THE
                         SECURITIES EXCHANGE ACT OF 1934
                               (AMENDMENT NO. __)
                                       AND
                                  SCHEDULE 13D
                    UNDER THE SECURITIES EXCHANGE ACT OF 1934
                                (AMENDMENT NO. 9)

                 Winthrop Growth Investors I Limited Partnership
- -------------------------------------------------------------------------------
                        (Name of Subject Company (Issuer)

                        AIMCO Properties, L.P. -- Offeror
- --------------------------------------------------------------------------------
            (Names of Filing Persons (Identifying Status as Offeror,
                            Issuer or Other Person))

                            Limited Partnership Units
- --------------------------------------------------------------------------------
                           (Title of Class Securities)

                                      None
- --------------------------------------------------------------------------------
                       (CUSIP Number of Class Securities)

                                 Patrick J. Foye
                            Executive Vice President
                   Apartment Investment And Management Company
                           Colorado Center, Tower Two
                   2000 South Colorado Boulevard, Suite 2-1000
                             Denver, Colorado 80222
                                 (303) 757-8081
- --------------------------------------------------------------------------------
            Name, address, and telephone numbers of person authorized
       to receive notices and communications on behalf of filing persons)

                                    Copy To:

                                Gregory M. Chait
                               Katherine M. Koops
                     Powell, Goldstein, Frazer & Murphy LLP
                   191 Peachtree Street, N.E., Sixteenth Floor
                             Atlanta, Georgia 30303
                                 (404) 572-6600

                            Calculation of Filing Fee

<Table>
<Caption>
        -----------------------------------------------------------------------
        Transaction valuation*            Amount of filing fee
        -----------------------------------------------------------------------
                                       
        $6,542,524                        $1,309
        -----------------------------------------------------------------------
</Table>

*    For purposes of calculating the fee only. This amount assumes the purchase
     of 14,039.75 units of limited partnership interest of the subject
     partnership for $466 per unit. The amount of the filing fee equals 1/50th
     of one percent of the aggregate of the cash offered by the bidder.

[ ]  Check the box if any part of the fee is offset as provided by Rule
     0-11(a)(2) and identify the filing with which the offsetting fee was
     previously paid. Identify the previous filing by registration statement
     number, or the Form or Schedule and the date of its filing.

Amount Previously Paid:  $                    Filing Party:

Form or Registration No.:                     Date Filed:

                                    ---------

[ ]  Check the box if the filing relates solely to preliminary communications
     made before the commencement of a tender offer.

Check the appropriate boxes below to designate any transactions to which the
statement relates:

        [ ]  Third-party tender offer      [ ]  going-private transaction
             subject to Rule 14d-1              subject to Rule 13e-3

        [X]  issuer tender offer           [X]  amendment to Schedule 13D under
             subject to Rule 13e-4              Rule 13d-2

Check the following box if the filing is a final amendment reporting the results
of the tender offer: [ ]


   2




CUSIP No.    NONE

1.    NAME OF REPORTING PERSON(S) S.S.# OR I.R.S. IDENTIFICATION NOS. OF ABOVE
      PERSONS (entities only)

             AIMCO PROPERTIES, L.P.
             84-1275721

2.    CHECK THE APPROPRIATE BOX IF A MEMBER OF GROUP
                                                                    (a)  [ ]
                                                                    (b)  [X]
3.    SEC USE ONLY

4.    SOURCE OF FUNDS

             WC, BK

5.    (CHECK IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO
      ITEMS 2(d) OR 2(e))                                                [ ]

6.    CITIZENSHIP OR PLACE OF ORGANIZATION

             Delaware

7.    NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON

      A.     SOLE VOTING POWER

      B.     SHARED VOTING POWER
                    4,236.91 Units

      C.     SOLE DISPOSITIVE POWER

      D.     SHARED DISPOSITIVE POWER
                    4,236.91 Units

8.    AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON
                    4,236.91 Units

9.    CHECK IF THE AGGREGATE AMOUNT IN ROW (7) EXCLUDES CERTAIN SHARES
                                                                         [ ]

10.   PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (7)

             Approximately 18.31%

11.   TYPE OF REPORTING PERSON

             PN


   3


CUSIP No.    NONE

1.    NAME OF REPORTING PERSON(S) S.S.# OR I.R.S. IDENTIFICATION NOS. OF
      ABOVE PERSONS (entities only)

             AIMCO-GP, INC.

2.    CHECK THE APPROPRIATE BOX IF A MEMBER OF GROUP
                                                                    (a)  [ ]
                                                                    (b)  [X]

3.    SEC USE ONLY

4.    SOURCE OF FUNDS

             Not Applicable

5.    (CHECK IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO
      ITEMS 2(d) OR 2(e))                                                [ ]

6.    CITIZENSHIP OR PLACE OF ORGANIZATION

             Delaware

7.    NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON

      A.     SOLE VOTING POWER


      B.     SHARED VOTING POWER
                    4,236.91 Units

      C.     SOLE DISPOSITIVE POWER

      D.     SHARED DISPOSITIVE POWER
                    4,236.91 Units

8.    AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON
                    4,236.91 Units

9.    CHECK IF THE AGGREGATE AMOUNT IN ROW (7) EXCLUDES CERTAIN SHARES
                                                                         [ ]
10.   PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (7)

             Approximately 18.31%

11.   TYPE OF REPORTING PERSON

             CO


   4


CUSIP No.    NONE

1.    NAME OF REPORTING PERSON(S) S.S.# OR I.R.S. IDENTIFICATION NOS. OF
      ABOVE PERSONS (entities only)

             APARTMENT INVESTMENT AND MANAGEMENT COMPANY
             84-129577

2.    CHECK THE APPROPRIATE BOX IF A MEMBER OF GROUP
                                                                    (a)  [ ]
                                                                    (b)  [X]

3.    SEC USE ONLY

4.    SOURCE OF FUNDS

             Not Applicable

5.    (CHECK IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO
      ITEMS 2(d) OR 2(e))                                                [ ]

6.    CITIZENSHIP OR PLACE OF ORGANIZATION

             Maryland

7.    NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON

      A.     SOLE VOTING POWER


      B.     SHARED VOTING POWER
                    9,109.25 Units

      C.     SOLE DISPOSITIVE POWER

      D.     SHARED DISPOSITIVE POWER
                    9,109.25 Units

8.    AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON
                    9,109.25 Units

9.    CHECK IF THE AGGREGATE AMOUNT IN ROW (7) EXCLUDES CERTAIN SHARES
                                                                         [ ]

10.   PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (7)

             Approximately 39.37%

11.   TYPE OF REPORTING PERSON

             CO


   5


CUSIP No.    NONE

1.    NAME OF REPORTING PERSON(S) S.S.# OR I.R.S. IDENTIFICATION NOS. OF
      ABOVE PERSONS (entities only)

             INSIGNIA FINANCIAL GROUP, INC.

2.    CHECK THE APPROPRIATE BOX IF A MEMBER OF GROUP
                                                                    (a)  [ ]
                                                                    (b)  [X]

3.    SEC USE ONLY

4.    SOURCE OF FUNDS

                  Not Applicable

5.    (CHECK IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO
      ITEMS 2(d) OR 2(e))                                                [ ]

6.    CITIZENSHIP OR PLACE OF ORGANIZATION

             Delaware

7.    NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON

      A.     SOLE VOTING POWER


      B.     SHARED VOTING POWER
                    4,872.34 Units

      C.     SOLE DISPOSITIVE POWER


      D.     SHARED DISPOSITIVE POWER
                    4,872.34 Units

8.    AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON
                    4,872.34 Units

9.    CHECK IF THE AGGREGATE AMOUNT IN ROW (7) EXCLUDES CERTAIN SHARES
                                                                         [ ]

10.   PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (7)

             Approximately 21.06%

11.   TYPE OF REPORTING PERSON

             CO

   6


TENDER OFFER STATEMENT/ AMENDMENT NO. 9 TO SCHEDULE 13D

     This Tender Offer Statement on Schedule TO relates to the tender offer by
AIMCO Properties, L.P., a Delaware limited partnership, to purchase all of the
outstanding units, or such lesser number of units as are properly tendered, of
limited partnership interest of Winthrop Growth Investors I Limited Partnership,
a Massachusetts limited partnership (the "Partnership"), at a price of $466 per
unit, subject to the conditions set forth in the Offer to Purchase dated August
30, 2001, and in the related Letter of Transmittal and Acknowledgment and
Agreement, which, as amended and supplemented from time to time, together
constitute the tender offer. Copies of the Offer to Purchase, Letter of
Transmittal and Acknowledgment and Agreement are filed with this Schedule TO as
Exhibits 1, 2 and 3, respectively. In addition, because AIMCO Properties, L.P.
is an affiliate of the Partnership, this Schedule TO is intended to satisfy the
reporting requirements of Rule 13e-4(c)(1) of the Securities Exchange Act of
1934, as amended. It also serves as Amendment No. 9 to the Schedule 13D filed by
AIMCO Properties, L.P. and certain of its affiliates.

     The information in Exhibits 1-3, 5(a)-(c) and 6, respectively, is
incorporated in this Schedule TO by reference in answer to items 1 through 11 of
Schedule TO and in response to Items 1 through 7 of Schedule 13D.

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


Item 12.   Exhibits.

          1    Offer to Purchase, dated August 30, 2001.

          2    Letter of Transmittal and related Instructions (included as Annex
               II to the Offer to Purchase attached as Exhibit (a)(1)).

          3    Acknowledgement and Agreement dated August 30, 2001.

          4    Letter, dated August 30, 2001, from AIMCO Properties, L.P. to the
               limited partners of the Partnership.

          5(a) Credit Agreement (Secured Revolving Credit Facility), dated as of
               August 16, 1999, among AIMCO Properties, L.P., Bank of America,
               Bank Boston, N.A., and First Union National Bank. (Exhibit 10.1
               to AIMCO's Current Report on Form 8-K, dated August 16, 1999 is
               incorporated herein by this reference.)

          5(b) Amended and Restated Credit Agreement, dated as of March 15,
               2000, among AIMCO Properties, L.P., Bank of America, Bank Boston,
               N.A., and First Union National Bank. (Exhibit 10.20 to AIMCO
               Properties, L.P.'s Annual Report on Form 10-K for the year ended
               December 31, 1999 is incorporated herein by this reference.)

          5(c) First Amendment to $345,000,000 Amended and Restated Credit
               Agreement, dated as of April 14, 2000, among AIMCO Properties,
               L.P., Bank of America, as Administrative Agent, and U.S. Bank
               National Association, as Lender. (Exhibit 10.4 to AIMCO's Current
               Report on Form 10-Q for quarter ended March 31, 2000 is
               incorporated herein by this reference.)

          6    Agreement of Joint Filing, dated August 30, 2001, among AIMCO,
               AIMCO-GP, AIMCO Properties, L.P. and Insignia Financial Group,
               Inc.

   7


                                    SIGNATURE

          After due inquiry and to the best of my knowledge and belief, I
certify that the information set forth in this statement is true, complete and
correct.


Date:  August 30, 2001
                                               AIMCO PROPERTIES, L.P.

                                               By: AIMCO-GP, INC.
                                                        (General Partner)

                                               By: /s/ Patrick J. Foye
                                                   -------------------------
                                                   Executive Vice President


                                               AIMCO-GP, INC.

                                               By: /s/ Patrick J. Foye
                                                   -------------------------
                                                   Executive Vice President


                                               APARTMENT INVESTMENT
                                               AND MANAGEMENT COMPANY

                                               By: /s/ Patrick J. Foye
                                                   -------------------------
                                                   Executive Vice President


                                               INSIGNIA FINANCIAL
                                               GROUP, INC.

                                               By: /s/ Patrick J. Foye
                                                   -------------------------
                                                   Executive Vice President



   8


                                  EXHIBIT INDEX

<Table>
<Caption>
EXHIBIT NO.   DESCRIPTION
- -----------   -----------
           
    1         Offer to Purchase, dated August 30, 2001.

    2         Letter of Transmittal and related Instructions (included as Annex
              II to the Offer to Purchase attached as Exhibit (a)(1)).

    3         Acknowledgement and Agreement dated August 30, 2001.

    4         Letter, dated August 30, 2001, from AIMCO Properties, L.P. to the
              limited partners of the Partnership.

    5(a)      Credit Agreement (Secured Revolving Credit Facility), dated as of
              August 16, 1999, among AIMCO Properties, L.P., Bank of America,
              Bank Boston, N.A., and First Union National Bank. (Exhibit 10.1 to
              AIMCO's Current Report on Form 8-K, dated August 16, 1999 is
              incorporated herein by this reference.)

    5(b)      Amended and Restated Credit Agreement, dated as of March 15, 2000,
              among AIMCO Properties, L.P., Bank of America, Bank Boston, N.A.,
              and First Union National Bank. (Exhibit 10.20 to AIMCO Properties,
              L.P.'s Annual Report on Form 10-K for the year ended December 31,
              1999 is incorporated herein by this reference.)

    5(c)      First Amendment to $345,000,000 Amended and Restated Credit
              Agreement, dated as of April 14, 2000, among AIMCO Properties,
              L.P., Bank of America, as Administrative Agent, and U.S. Bank
              National Association, as Lender. (Exhibit 10.4 to AIMCO's Current
              Report on Form 10-Q for quarter ended March 31, 2000 is
              incorporated herein by this reference.)

    6         Agreement of Joint Filing, dated August 30, 2001, among AIMCO,
              AIMCO-GP, AIMCO Properties, L.P. and Insignia Financial Group,
              Inc.
</Table>