<PAGE>

                                                                    EXHIBIT 31.2
                                                                    ------------

           WINTHROP RESIDENTIAL ASSOCIATES III, A LIMITED PARTNERSHIP
           ----------------------------------------------------------
                         FORM 10-QSB SEPTEMBER 30, 2003
                         ------------------------------


                                 CERTIFICATIONS

          I, Thomas C. Staples, certify that:

     1.   I have reviewed this quarterly report on Form 10-QSB of Winthrop
          Residential Associates III, A Limited Partnership;

     2.   Based on my knowledge, this quarterly report does not contain any
          untrue statement of a material fact or omit to state a material fact
          necessary to make the statements made, in light of the circumstances
          under which such statements were made, not misleading with respect to
          the period covered by this quarterly report;

     3.   Based on my knowledge, the financial statements, and other financial
          information included in this quarterly report, fairly present in all
          material respects the financial condition, results of operations and
          cash flows of the registrant as of, and for, the periods presented in
          this quarterly report;

     4.   The registrant's other certifying officer and I are responsible for
          establishing and maintaining disclosure controls and procedures (as
          defined in Exchange Act Rules 13a-15(e) and 15d-15(e)) for the
          registrant and have:

          a)   designed such disclosure controls and procedures, or caused such
               disclosure controls and procedures to be designed under our
               supervision, to ensure that material information relating to the
               registrant is made known to us, particularly during the period in
               which this quarterly report is being prepared;

          b)   evaluated the effectiveness of the registrant's disclosure
               controls and procedures and presented in this report our
               conclusions about the effectiveness of the disclosure controls
               and procedures, as of the end of the period covered by this
               report based on such evaluation; and

          c)   disclosed in this report any change in the registrant's internal
               control over financial reporting that occurred during the
               registrant's most recent fiscal quarter that has materially
               affected, or is reasonably likely to materially affect, the
               registrant's internal control over financial reporting;




<PAGE>

                                                                    EXHIBIT 31.2
                                                                    ------------

           WINTHROP RESIDENTIAL ASSOCIATES III, A LIMITED PARTNERSHIP
           ----------------------------------------------------------
                         FORM 10-QSB SEPTEMBER 30, 2003
                         ------------------------------

     5.   The registrant's other certifying officer and I have disclosed, based
          on our most recent evaluation of internal control over financial
          reporting, to the registrant's auditors and the audit committee of
          registrant's board of directors (or persons performing the equivalent
          functions):

          a)   all significant deficiencies and material weaknesses in the
               design or operation of internal control over financial reporting
               which are reasonably likely to adversely affect the registrant's
               ability to record, process, summarize and report financial
               information; and

          b)   any fraud, whether or not material, that involves management or
               other employees who have a significant role in the registrant's
               internal control over financial reporting.



     Date:   November 13, 2003              /s/ Thomas C. Staples
                                           ------------------------------------
                                            Thomas C. Staples
                                            Chief Financial Officer