UNITED STATES
                      SECURITIES AND EXCHANGE COMMISSION
                            WASHINGTON, D.C. 20549

                                    ------

                                   FORM 10-K

(Mark One)

     [X]  ANNUAL REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES
     EXCHANGE ACT OF 1934

     For the fiscal year ended:  December 31, 2001
                                 -----------------

                                      OR

     [ ]  TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES
     EXCHANGE ACT OF 1934

     For the transition period from               to
                                   -------------    -------------

                     Commission file number: 333-64564-18
                                             ------------


                  CWMBS, Inc., Alternative Loan Trust 2001-13
              Mortgage Pass-Through Certificates, Series 2001-31
              --------------------------------------------------
            (Exact name of Registrant as specified in its charter)


              Delaware                                 95-4449516
-------------------------------           ------------------------------------
(State or other jurisdiction of           (IRS Employer Identification Number)
incorporation or organization)

c/o  The Bank of New York
     101 Barclay Street
     New York, New York                                  10286
----------------------------------------  ------------------------------------
(Address of principal executive offices)              (Zip Code)

Registrant's telephone number, including area code:   (212) 815-2007
                                                      --------------

Securities registered pursuant to Section 12(b) of the Act:  None
                                                             ----

Securities registered pursuant to Section 12(g) of the Act:  None
                                                             ----

<PAGE>

Indicate by check mark whether the Registrant (1) has filed all reports
required to be filed by Section 13 or 15(d) of the Securities Exchange Act of
1934 during the preceding 12 months (or for such shorter period that the
Registrant was required to file such reports), and (2) has been subject to
such filing requirements for the past 90 days. Yes X   No
                                                  ---    ---

Indicate by check mark if disclosure of delinquent filers pursuant to Item 405
of Regulation S-K (Section 229.405 of this chapter) is not contained herein,
and will not be contained, to the best of Registrant's knowledge, in
definitive proxy or information statements incorporated by reference in Part
III of this Form 10-K or any amendment to this Form 10-K. [ ]

State the aggregate market value of the voting and non-voting common equity
held by non-affiliates of the Registrant: Not applicable
                                          --------------

Indicate the number of shares outstanding as of each of the registrant's
classes of common stock, of December 31, 2001: Not applicable
                                               --------------



                                      2

<PAGE>

DOCUMENTS INCORPORATED BY REFERENCE

                                     None.

                                 *     *     *


     This Annual Report on Form 10-K (the "Report") is filed with respect to
the trust fund entitled Alternative Loan Trust 2001-13 (the "Trust Fund")
formed pursuant to the pooling and servicing agreement dated as of December 1,
2001 (the "Pooling and Servicing Agreement") among CWMBS, Inc., as depositor
(the "Company"), Countrywide Home Loans, Inc., as seller and master servicer
(the "Master Servicer"), and The Bank of New York, as trustee (the "Trustee"),
for the issuance of CWMBS, Inc., Mortgage Pass-Through Certificates, Series
2001-31 (the "Certificates"). Certain information otherwise required to be
included in this Report by the Instructions to Form 10-K has been omitted in
reliance on the relief granted to the Company in CWMBS, Inc. (February 3,
1994) (the "Relief Letter").



                                      3

<PAGE>

                                    PART I


ITEM 1.  BUSINESS

         Not applicable.  See the Relief Letter.

ITEM 2.  PROPERTIES

         Not applicable.  See the Relief Letter.

ITEM 3.  LEGAL PROCEEDINGS

         There were no material pending legal proceedings relating to
         the Trust Fund to which any of the Trust Fund, the Trustee,
         the Master Servicer or the Company was a party or of which
         any of their respective properties was the subject during
         the fiscal year covered by this Report, nor is the Company
         aware of any such proceedings contemplated by governmental
         authorities.

ITEM 4.  SUBMISSION OF MATTERS TO A VOTE OF SECURITY HOLDERS

         No matter was submitted to a vote of Certificateholders, and
         no Certificateholder consent was solicited during the fiscal
         year covered by this Report.



                                      4

<PAGE>

                                    PART II


ITEM 5.   MARKET FOR REGISTRANT'S COMMON EQUITY AND RELATED STOCKHOLDER MATTERS

          (a)  Market Information. There is no established public trading
               market for the Certificates.

          (b)  Holders. As of December 31, 2001 there were less than 300
               holders of record of the Certificates.

          (c)  Dividends. Not applicable. See the Relief Letter. (Information
               as to distributions to Certificateholders is provided in the
               Registrant's monthly filings on Form 8-K.)

          (d)  Item 701 of Regulation S-K. Not applicable. See the Relief
               Letter.

          (e)  Rule 463 of the Securities Act of 1933. Not applicable. See the
               Relief Letter.

ITEM 6.   SELECTED FINANCIAL DATA

          Not applicable.  See the Relief Letter.

ITEM 7.   MANAGEMENT'S DISCUSSION AND ANALYSIS OF FINANCIAL CONDITION AND
          RESULTS OF OPERATIONS

          Not applicable.  See the Relief Letter.

ITEM 7A   QUANTITATIVE AND QUALITATIVE DISCLOSURES ABOUT MARKET RISK

          Not applicable.  See the Relief Letter.

ITEM 8.   FINANCIAL STATEMENTS AND SUPPLEMENTARY DATA

          Not applicable.  See the Relief Letter.

ITEM 9.   CHANGES IN AND DISAGREEMENTS WITH ACCOUNTANTS ON ACCOUNTING AND
          FINANCIAL DISCLOSURE

          None.



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<PAGE>

                                   PART III


ITEM 10.  DIRECTORS AND EXECUTIVE OFFICERS OF THE REGISTRANT

          Not applicable.  See the Relief Letter.

ITEM 11.  EXECUTIVE COMPENSATION

          Not applicable.  See the Relief Letter.

ITEM 12.  SECURITY OWNERSHIP OF CERTAIN BENEFICIAL OWNERS AND MANAGEMENT

          (a)  Not applicable.  See the Relief Letter.

          (b)  Not applicable.  See the Relief Letter.

          (c)  Not applicable.  See the Relief Letter.

ITEM 13.  CERTAIN RELATIONSHIPS AND RELATED TRANSACTIONS

          Not applicable.  See the Relief Letter.



                                      6

<PAGE>

                                    PART IV


ITEM 14.  EXHIBITS, FINANCIAL STATEMENT SCHEDULES, AND REPORTS ON FORM 8-K

          (a)  (1)  Pursuant to the Pooling and Servicing Agreement, the Master
                    Servicer is required (i) to deliver an annual statement as
                    to compliance with the provisions of the Pooling and
                    Servicing Agreement and certain other matters (the "Annual
                    Statement of the Master Servicer") and (ii) to cause a
                    firm of independent public accountants to deliver an
                    annual report as to compliance with the servicing
                    provisions of the Pooling and Servicing Agreement (the
                    "Annual Report of the Firm of Accountants"). The Annual
                    Statement of the Master Servicer is attached as Exhibit
                    99.1 to this Report. The Annual Report of the Firm of
                    Accountants is attached as Exhibit 99.2 to this Report.

               (2)  Not applicable.

               (3)  The required exhibits are as follows:

                                   Exhibit 3(i): Copy of Company's Certificate
                    of Incorporation (Filed as an Exhibit to Registration
                    Statement on Form S-3 (File No.33-63714)).

                                   Exhibit 3(ii): Copy of Company's By-laws
                    (Filed as an Exhibit to Registration Statement on Form S-3
                    (File No. 33-63714)).

                                   Exhibit 4: Pooling and Servicing Agreement
                    (Filed as part of the Registrant's Current Report on Form
                    8-K filed on March 11, 2002).

                                   Exhibit 99.1: Annual Statement of the
                    Master Servicer.

                                   Exhibit 99.2: Annual Report of the Firm of
                    Accountants.



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<PAGE>



          (b)  Current Reports on Form 8-K filed during the last quarter ended
          December 31, 2001:

<TABLE>
<CAPTION>
               Date of Current Report                      Item Reported
               ----------------------                      -------------
<S>                                           <C>
           December 21, 2001                  Consolidated financial statements of MBIA Inc. and
                                              its subsidiaries and MBIA Insurance Corporation and
                                              its subsidiaries; consent of PricewaterhouseCoopers
                                              LLP

           December 28, 2001                  Legality Opinion and Consent of Sidley Austin Brown
                                              & Wood LLP

           December 28, 2001                  Computational Materials of Bear, Stearns & Co. Inc.
</TABLE>

          (c)  See subparagraph (a)(3) above.

          (d)  Not applicable.  See the Relief Letter.

     SUPPLEMENTAL INFORMATION TO BE FURNISHED WITH REPORTS FILED PURSUANT TO
SECTION 15(d) OF THE ACT BY REGISTRANTS WHICH HAVE NOT REGISTERED SECURITIES
PURSUANT TO SECTION 12 OF THE ACT.

     No such annual report, proxy statement, form of proxy or other soliciting
material has been sent to Certificateholders. See the Relief Letter.



                                      8

<PAGE>

                                  SIGNATURES

     Pursuant to the requirements of Section 13 or 15(d) of the Securities
Exchange Act of 1934, the Registrant has duly caused this Report to be signed
on its behalf by the undersigned, thereunto duly authorized.

                                      CWMBS, INC.,
                                      ALTERNATIVE LOAN TRUST 2001-13,
                                      MORTGAGE PASS-THROUGH CERTIFICATES,
                                      SERIES 2001-31


                                By:  The Bank of New York,
                                     as Trustee*


                                By:  /s/  Courtney Bartholomew
                                     -----------------------------------------
                                     Name:   Courtney Bartholomew
                                     Title:  Vice President

                                Date:  March 25, 2002









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*    This Report is being filed by the Trustee on behalf of the Trust Fund.
     The Trust Fund does not have any officers or directors.



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<PAGE>

                                 EXHIBIT INDEX


                                                                    Sequential
Exhibit Document                                                   Page Number
------- --------                                                   -----------


3(i)        Company's Certificate of Incorporation (Filed as an
            Exhibit to Registration Statement on Form S-3 (File No.
            33-63714)) *

3(ii)       Company's By-laws (Filed as an Exhibit to Registration
            Statement on Form S-3 (File No. 33-63714)) *

4           Pooling and Servicing Agreement (Filed as part of the
            Company's Current Report on Form 8-K filed on March 11,
            2002) *

99.1        Annual Statement of the Master Servicer.........................12

99.2        Annual Report of the Firm of Accountants........................14












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

*    Incorporated herein by reference.



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