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. 3)
                                (FINAL AMENDMENT)

                                       AND
                                  SCHEDULE 13D
                    UNDER THE SECURITIES EXCHANGE ACT OF 1934
                               (AMENDMENT NO. 20)


                          National Property Investors 4
                          -----------------------------
                       (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
                   Apartment Investment And Management Company
                           Colorado Center, Tower Two
                   2000 South Colorado Boulevard, Suite 2-1000
                             Denver, Colorado 80222
                                 (303) 757-8101

                 (Name, address, and telephone numbers of person
               authorized to receive notices and communications on
                            behalf of filing persons)

                                    Copy To:

                              Jonathan L. Friedman
                    Skadden, Arps, Slate, Meagher & Flom LLP
                       300 South Grand Avenue, 34th Floor
                          Los Angeles, California 90071
                                 (213) 687-5000




   2



                            Calculation of Filing Fee




Transaction valuation*                                     Amount of filing fee
                                                        
$4,553,342                                                 $910.67


*        For purposes of calculating the fee only. This amount assumes the
         purchase of 16,802 units of limited partnership interest of the subject
         partnership for $271 per unit. The amount of the filing fee, calculated
         in accordance with Section 14(g)(1)(B)(3) and Rule 0-11(d) under the
         Securities Exchange Act of 1934, as amended, equals 1/50th of one
         percent of the aggregate of the cash offered by the bidder.

[X]      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:  $910.67            Filing Party: AIMCO Properties, L.P.

Form or Registration No.:  Schedule TO      Date Filed: August 8, 2000



[ ] 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:

[X] third-party tender offer subject to Rule 14d-1

[ ] issuer tender offer subject to Rule 13e-4

[ ] going-private transaction subject to Rule 13e-3

[X] amendment to Schedule 13D under Rule 13d-2

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




                                        2

   3



CUSIP No. NONE

1.       NAME OF REPORTING PERSONS
         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

NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON

7.       SOLE VOTING POWER

                  --

8.       SHARED VOTING POWER

                  11,111 Units

9.       SOLE DISPOSITIVE POWER

                  --

10.      SHARED DISPOSITIVE POWER

                  11,111 Units

11.      AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

                  11,111 Units

12.      CHECK IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES
                                                                             [ ]

13.      PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)

                  Approximately 18.52%

14.      TYPE OF REPORTING PERSON

                  PN


                                        3

   4



CUSIP No.   NONE

1.       NAME OF REPORTING PERSONS
         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

NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON

7.       SOLE VOTING POWER

                  --

8.       SHARED VOTING POWER

                  11,111 Units

9.       SOLE DISPOSITIVE POWER

                  --

10.      SHARED DISPOSITIVE POWER

                  11,111 Units

11.      AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

                  11,111 Units

12.      CHECK IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES
                                                                             [ ]

13.      PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)

                  Approximately 18.52%

14.      TYPE OF REPORTING PERSON

                  CO



                                        4

   5



CUSIP No. NONE

1.       NAME OF REPORTING PERSONS
         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

NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON

7.       SOLE VOTING POWER

                  --

8.       SHARED VOTING POWER

                  43,636 Units

9.       SOLE DISPOSITIVE POWER

                  --

10.      SHARED DISPOSITIVE POWER

                  43,636 Units

11.      AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

                  43,636 Units

12.      CHECK IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES
                                                                             [ ]

13.      PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)

                  Approximately 72.21%

14.      TYPE OF REPORTING PERSON

                  CO


                                        5

   6



CUSIP No. NONE

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

                  INSIGNIA PROPERTIES, L.P.

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

NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON

7.       SOLE VOTING POWER

                  --

8.       SHARED VOTING POWER

                  32,525 Units

9.       SOLE DISPOSITIVE POWER

                  --

10.      SHARED DISPOSITIVE POWER

                  32,525 Units

11.      AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

                  32,525 Units

12.      CHECK IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES
                                                                             [ ]

13.      PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)

                  Approximately 54.20%

14.      TYPE OF REPORTING PERSON

                  PN


                                       6

   7



CUSIP No. NONE

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

                  AIMCO/IPT, 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

NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON

7.       SOLE VOTING POWER

                  --

8.       SHARED VOTING POWER

                  32,525 Units

9.       SOLE DISPOSITIVE POWER

                  --

10.      SHARED DISPOSITIVE POWER

                  32,525 Units

11.      AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

                  32,525 Units

12.      CHECK IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES
                                                                             [ ]

13.      PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)

                  Approximately 54.20%

14.      TYPE OF REPORTING PERSON

                  CO



                                        7

   8



CUSIP No.   NONE

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

                  IPLP ACQUISITION I, L.L.C.

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

NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON

7.       SOLE VOTING POWER

                  --

8.       SHARED VOTING POWER

                  4,452 Units

9.       SOLE DISPOSITIVE POWER

                  --

10.      SHARED DISPOSITIVE POWER

                  4,452 Units

11.      AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

                  4,452 Units

12.      CHECK IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES
                                                                             [ ]

13.      PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)

                  Approximately 7.42%

14.      TYPE OF REPORTING PERSON

                  OO



                                        8

   9
                   AMENDMENT NO. 3 TO TENDER OFFER STATEMENT/
                        AMENDMENT NO. 20 TO SCHEDULE 13D

         This Statement (the "Statement") constitutes (a) Amendment No. 3 to the
Tender Offer Statement on Schedule TO of AIMCO Properties, L.P. (the "AIMCO
OP"), relating to an offer to purchase units of limited partnership interest
("Units") of National Property Investors 4 (the "Partnership"); and (b)
Amendment No. 20 to the Schedule 13D (the "Schedule 13D") originally filed with
the Securities and Exchange Commission (the "Commission") on August 29, 1995, by
Insignia Financial Group, Inc. ("Insignia"), IFGP Corporation ("IFGP"), Insignia
NPI, L.L.C. ("NPI"), Riverside Drive, L.L.C. ("Riverside") and Andrew L. Farkas,
as amended by (i) Amendment No. 1, filed with the Commission on January 30,
1996, by Insignia, IFGP, NPI, Riverside, Insignia Commercial Group, Inc.
("Commercial"), Insignia Properties Corporation ("IPC") and Andrew L. Farkas,
(ii) Amendment No. 2, filed with the Commission on February 28, 1996, by
Insignia, IFGP, NPI, Riverside, Commercial, IPC and Andrew L. Farkas, (iii)
Amendment No. 3, filed with the Commission on January 16, 1997, by Insignia,
Insignia Properties, L.P. ("IPLP"), Insignia Properties Trust ("IPT") and Andrew
L. Farkas, (iv) Amendment No. 4, filed with the Commission on August 28, 1997,
by IPLP Acquisition I, L.L.C. ("IPLP Acquisition"), IPLP, IPT, Insignia and
Andrew L. Farkas, (v) Amendment No. 5, filed with the Commission on September
26, 1997, by IPLP Acquisition, IPLP, IPT, Insignia and Andrew L. Farkas, (vi)
Amendment No. 6, filed with the Commission on October 1, 1997, by IPLP
Acquisition, IPLP, IPT, Insignia and Andrew L. Farkas, (vii) Amendment No. 7,
filed with the Commission on October 3, 1997, by IPLP Acquisition, IPLP, IPT,
Insignia and Andrew L. Farkas, (viii) Amendment No. 8, filed with the Commission
on October 7, 1997, by IPLP Acquisition, IPLP, IPT, Insignia and Andrew L.
Farkas, (ix) Amendment No. 9, filed with the Commission on November 10, 1997, by
IPLP Acquisition, IPLP, IPT, Insignia and Andrew L. Farkas, (x) Amendment No.
10, filed with the Commission on October 26, 1998, by IPLP Acquisition, IPLP,
IPT, AIMCO OP, AIMCO-GP, Inc. ("AIMCO-GP") and Apartment Investment and
Management Company ("AIMCO"), (xi) Amendment No. 11, filed with the Commission
on June 10, 1999, by IPLP Acquisition, AIMCO/IPT, Inc. ("AIMCO/IPT"), IPLP,
AIMCO OP, AIMCO-GP and AIMCO, (xii) Amendment No. 12, filed with the Commission
on July 1, 1999, by IPLP Acquisition, AIMCO/IPT, IPLP, AIMCO OP, AIMCO-GP and
AIMCO, (xiii) Amendment No. 13, filed with the Commission on August 6, 1999, by
IPLP Acquisition, AIMCO/IPT, IPLP, AIMCO OP, AIMCO-GP and AIMCO, (xiv) Amendment
No. 14, filed with the Commission on November 17, 1999, by IPLP Acquisition,
AIMCO/IPT, IPLP, AIMCO OP, AIMCO-GP and AIMCO, (xv) Amendment No. 15, dated
December 16, 1999, by IPLP Acquisition, AIMCO/IPT, IPLP, AIMCO OP, AIMCO-GP and
AIMCO, (xvi) Amendment No. 16, dated January 10, 2000, by IPLP Acquisition,
AIMCO/IPT, IPLP, AIMCO OP, AIMCO-GP and AIMCO, (xvii) Amendment No. 17, dated
August 7, 2000, by IPLP Acquisition, AIMCO/IPT, IPLP, AIMCO OP, AIMCO-GP and
AIMCO, (xviii) Amendment No. 18, dated September 6, 2000, by IPLP Acquisition,
AIMCO/IPT, IPLP, AIMCO OP, AIMCO-GP and AIMCO and (xix) Amendment No. 19, dated
September 21, 2000, by IPLP Acquisition, AIMCO/IPT, IPLP, AIMCO OP, AIMCO-GP and
AIMCO.

                                   ----------



                                        9

   10



Item 8. Interest in Securities of the Subject Company

         At 5:00 p.m., New York time, on Thursday, September 28, 2000, the offer
expired pursuant to its terms. A total of 709 Units, representing approximately
1.2% of the outstanding Units, were validly tendered and not withdrawn pursuant
to the offer. AIMCO OP has accepted for payment all of those Units for $271 per
Unit.

         Since July 1, 2000, AIMCO OP has purchased in privately negotiated
transactions or through the facilities of the American Partnership Board, the
following Units in the Partnership:




         DATE              NUMBER OF UNITS               SALE  PRICE PER UNIT
         ----           --------------------------       --------------------
                                                   
           8/1                      3                       $    250.84
          9/29                     73                            (1)



- ----------

(1)      The Units were purchased as part of a group purchase of 3,507.65 units
         in various partnerships for an aggregate price of $950,000.



                                       10

   11



                                    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:  October 18, 2000

                                             AIMCO PROPERTIES, L.P.

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

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

                                             IPLP ACQUISITION I, L.L.C.

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

                                             AIMCO/IPT, INC.

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

                                             INSIGNIA PROPERTIES, L.P.

                                             By: AIMCO/IPT, 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





                                       11