EXHIBIT 10.37

                                 SIXTH AMENDMENT
                                       OF
                         USG CORPORATION RETIREMENT PLAN

            (As Amended and Restated Effective as of January 1, 1999)

      WHEREAS, USG Corporation Retirement Plan (the "plan") is maintained by USG
Corporation (the "company"), which plan was amended and restated on December 29,
1999, effective as of January 1, 1999; and

      WHEREAS, it now is deemed desirable and in the best interests of the
employers under the plan and their employees to further amend the plan;

      NOW, THEREFORE, pursuant to the amending power reserved to the company
under subsection 14.1 of the plan, the plan is further amended by substituting
the following for paragraph A-2(i) of Exhibit A to the Plan, effective January
1, 2006:

            "(i)  from January 1, 1992 through December 31, 2005, 8 percent per
                  annum or such higher or lower rate equal to the nearest whole
                  percentage point below the average rate then available for
                  90-day U.S. Government Treasury Bills, as may be specified for
                  a designated period by the committee at its discretion by
                  writing filed with the plan's actuary; and

            (j)   after December 31, 2005, 120 percent of the Federal mid-term
                  rate (as in effect for the first month of a plan year).
                  Notwithstanding the foregoing, for lump sum payments made
                  after December 31, 2005 pursuant to the first sentence of
                  subsection 5.5 or the first sentence of subsection 6.3, the
                  plan interest rate for the period January 1, 1992 through
                  December 31, 2005 shall not be less than 120 percent of the
                  Federal mid-term rate (as in effect for the first month of the
                  applicable calendar year). The lump sum rate for calculating
                  the lump sum actuarially equivalent value of a participant's
                  benefits under the plan continues to be the rate set forth in
                  Paragraph A-4 below."



      IN WITNESS WHEREOF, the company has caused these presents to be signed by
its officer thereunto duly authorized this 19th day of January, 2006.

                                          USG CORPORATION

                                          By: /s/ Peter K. Maitland
                                              ----------------------------------
                                              Vice President, Compensation
                                              Benefits And Administration

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