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                                                                  EXHIBIT 10.20
                                FIRST AMENDMENT
                                       TO
                             STOCKHOLDERS AGREEMENT


          This First Amendment to Stockholders Agreement (this "Amendment"),
dated as of January 21, 2002, hereby amends that certain Stockholders' Agreement
(the "Existing Agreement"), dated July 8, 1998, by and among Century Maintenance
Supply, Inc., a Delaware corporation (the "Company"), FS Equity Partners IV,
L.P., a Delaware limited partnership ("FSEP IV" or the "FS Stockholder"),
William C. Johnson ("Johnson"), The Parthenon Group, Inc., a Delaware
corporation ("Parthenon" and collectively with Johnson, the "Additional
Stockholders"), Dennis C. Bearden ("Bearden") and Century Airconditioning
Supply, Inc., a Texas corporation ("CAC", and collectively with Bearden, the
"Existing Stockholders"). Capitalized terms not otherwise defined herein shall
have the meaning ascribed to such terms in the Existing Agreement.


                                R E C I T A L S
                                - - - - - - - -

          WHEREAS, the Company, FSEP IV, Johnson, Parthenon and the Existing
Stockholders, are parties to the Existing Agreement.

          WHEREAS, Section 11 of the Existing Agreement permits the Existing
Agreement to be amended solely by FSEP IV so long as such amendment does not
prejudice the existing rights of the Existing Stockholders, Johnson or
Parthenon.

          WHEREAS, FSEP IV, pursuant to Section 11 of the Existing Agreement,
desires to add Joseph Semmer ("Semmer") as a party to the Existing Agreement on
terms and conditions which do not prejudice the rights of the Existing
Stockholders, Johnson or Parthenon.

          WHEREAS, Semmer, in connection with his acquisition of Company common
stock and appointment as the Company's Chief Executive Officer, has agreed to
become a party to the Existing Agreement.

          NOW, THEREFORE, Semmer hereby agrees to be bound by the terms and
conditions of the Existing Agreement, as amended by this Amendment, and FSEP IV
hereby consents and agrees to amend the Existing Agreement as follows:

          1.   Joseph Semmer.  The Existing Agreement is hereby amended by
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adding the following definition after the definition of "Securities Act" and
before the definition of "Stockholders":

          "Semmer:  Joseph Semmer."
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          2.   Additional Stockholders.  The definition of "Additional
               -----------------------
Stockholders" in the Existing Agreement is hereby amended to read in its
entirety as follows:

          "Johnson, Parthenon and Semmer."

          3.   Permitted Transferee.  The definition of "Permitted Transferee"
               --------------------
in the Existing Agreement is hereby amended by removing clause (iii) and
substituting in its place a new clause (iii) as follows:

          "(iii) with respect to Bearden, Johnson and Semmer, a family
          trust, limited partnership, corporation or other entity
          established by Bearden, Johnson or Semmer, as applicable,
          all of the beneficiaries or owners of which are immediate
          family members of Bearden, Johnson or Semmer, as applicable,
          (provided, that in the case of any entity established by
          Bearden, Johnson or Semmer, as applicable, pursuant to this
          subparagraph (iii) other than such family trust, the owners
          thereof shall specifically agree that, notwithstanding
          anything contained in this Agreement to the contrary, such
          owners shall not further Transfer their ownership interests
          in such entity to any other Person), and"

          4.   Rights Upon Issuance of Additional Securities.  Section 2 of the
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Existing Agreement is hereby amended and restated to read as follows:

          "The Company hereby grants to each Initial Stockholder,
          Johnson and Semmer (Johnson and Semmer collectively with the
          Initial Stockholders, the "Notified Stockholders") the
          following rights with respect to any and all proposed
          issuances or sales of Additional Securities by the Company:"

          5.   Termination and Assignment.  Section 2.5 of the Existing
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Agreement is hereby amended by removing clause (iii) and substituting in its
place a new clause (iii) as follows:

          "(iii) with respect to Johnson and Semmer, at such time that
          the FS Stockholder's rights under this Section 2.5 shall
          have terminated pursuant to subparagraph (ii) hereof."

          6.   Transfer Restrictions Binding Stockholders.  The final sentence
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of Section 5.1(a) of the Existing Agreement is hereby amended and restated to
read as follows:

          "The Transfer of Securities from any Stockholder to a
          Permitted Transferee may be made without complying with
          Section 5.2; provided, that each of such transferees
          executes a written undertaking to be and becomes bound by
          this Agreement in the
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          same manner and to the same extent as such Stockholder and,
          in the case of Permitted Transferees of the Existing
          Stockholders, Johnson, Parthenon or Semmer, respectively,
          (i) executes an irrevocable power of attorney appointing
          Bearden, Johnson, Richard Crosier and Steven Smith, or
          Semmer, respectively (or an individual designated by such
          individuals, as applicable, if such individual is unable to
          act due to death or disability) as such transferee's
          attorney-in-fact with sole irrevocable power and authority
          to make all decisions on behalf of and take all actions
          required to be taken by such transferee in connection with
          this Agreement, including (without limitation) any required
          sale of Securities pursuant to Section 4 hereof, and (ii) if
          requested by the FS Stockholder, delivers an opinion of
          legal counsel reasonably satisfactory to the FS Stockholder
          that such undertaking is binding and enforceable."

          7.   Notices.  Section 13 of the Existing Agreement is hereby amended
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by adding the following immediately after the "Facsimile:  (617) 526-5000":

          "If to Semmer:

               Joseph Semmer
               ____________________
               ____________________
               ____________________
               Telecopy No.:        "
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          IN WITNESS WHEREOF, the undersigned have executed this Amendment as of
the date first set forth above.



                         FS EQUITY PARTNERS IV, L.P.
                         a Delaware limited partnership

                         By:  FS Capital Partners, LLC
                         Its: General Partner


                              By: /s/ J. Frederick Simmons
                                  ----------------------------------
                                    J. Frederick Simmons
                                    Managing Member



                         JOSEPH SEMMER


                         /s/ Joseph Semmer
                         -------------------------------------------