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                                                                   EXHIBIT (10b)

                                 FIRST AMENDMENT
                                     TO THE
                           1995 LONG-TERM EQUITY PLAN
                               OF USG CORPORATION


     FIRST AMENDMENT (this "First Amendment"), to the 1995 Long-term Equity Plan
of USG Corporation originally approved by the stockholders of the Corporation on
May 10, 1995 (the "Plan").

WHEREAS, the Compensation and Organization Committee of the Board of Directors
of USG Corporation (the "Corporation") has approved an amendment to the Plan to
impose additional conditions on certain awards under the Plan;

NOW, THEREFORE, in consideration of the premises, the Plan is hereby amended as
set forth below:

1.   Section 8(e) of the Plan is hereby amended by the addition of the following
     two (2) sentences at the end thereof:

          "In the event the Committee permits the surrender of previously-owned
          shares of Common Stock as payment for the exercise price of any award
          under the Plan, such shares shall have been beneficially owned by the
          grantee for not less than six (6) months and otherwise qualify as
          "mature" shares under Generally Accepted Accounting Principles. In the
          event the Committee permits the reduction of shares of Common Stock
          subject to any award under the Plan in order to satisfy tax
          withholding, such reduction may not exceed the then statutorily
          required rate of withholding."

2.   Except as expressly amended and modified by this First Amendment, the Plan
     is hereby ratified and confirmed in all respects.

     IN WITNESS WHEREOF, the Corporation has caused this First Amendment to be
executed by its officers thereunto duly authorized as of the 27th day of June,
2000


                                   USG CORPORATION


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

Attest:


/s/ Dean H. Goossen
- -------------------------
Dean H. Goossen
Corporate Secretary