SECURITIES AND EXCHANGE COMMISSION
                      Washington, D.C.  20549

                           SCHEDULE 13G
             Under the Securities Exchange Act of 1934

                          (Amendment #3)*

                          USG Corporation
     ________________________________________________________
                         (Name of Issuer)


                           Common Stock
      _______________________________________________________
                  (Title of Class and Securities)

                             903293405
      _______________________________________________________

               (CUSIP Number of Class of Securities)


Check the appropriate box to designate the rule pursuant to which
this
Schedule is filed:

/X/  Rule 13d-1(b)
/ /  Rule 13d-1(c)
/ /  Rule 13d-1(d)

* The remainder of this cover page shall be filled out for a

reporting person's initial filing on this form with respect to the

subject class of securities, and for any subsequent amendment

containing information which would alter the disclosures provided

in a prior page.



The information required in the remainder of this cover page shall

not be deemed to be "filed" for the purpose of Section 18 of the

Securities Exchange Act of 1934 ("Act") or otherwise subject to
the

liabilities of that section of the Act but shall be subject to all

other provisions of the Act (however, see the Notes).



                  (Continued on following page(s))




CUSIP No. 903293405                               13G
__________________________________________________________________
___________
(1)  NAMES OF REPORTING PERSONS
     Southeastern Asset Management, Inc.      I.D. No. 62-0951781
__________________________________________________________________
___________
(2)  CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP:
                                              (a)
                                              (b) X
__________________________________________________________________
___________
(3)  SEC USE ONLY
__________________________________________________________________
___________
(4)  CITIZENSHIP OR PLACE OF ORGANIZATION
     Tennessee
__________________________________________________________________
___________
                                   :(5) SOLE VOTING POWER
                                   :   (Discretionary Accounts)
NUMBER OF SHARES BENEFICIALLY      :     259,100 shares
OWNED BY EACH REPORTING PERSON
__________________________________________
WITH                               :(6) SHARED OR NO VOTING POWER

                                         2,334,800 shares (shared)
                                           458,800 shares (No
Vote)

__________________________________________
                                   :(7) SOLE DISPOSITIVE POWER
                                        (Discretionary Accounts)
                                   :      717,900 shares

__________________________________________
                                   :(8)  SHARED DISPOSITIVE POWER

                                   :     2,334,800 shares (Shared)

__________________________________________________________________
___________
(9)  AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON
      (Discretionary & Non-discretionary Accounts)
        3,052,700 shares
__________________________________________________________________
___________
(10)  CHECK BOX IF THE AGGREGATE AMOUNT IN ROW 9 EXCLUDES
      CERTAIN SHARES
__________________________________________________________________
___________
(11)  PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW 9
       7.1 %
__________________________________________________________________
___________
(12)  TYPE OF REPORTING PERSON
      IA
__________________________________________________________________
___________


CUSIP No. 903293405                               13G
__________________________________________________________________
___________
(1)  NAMES OF REPORTING PERSONS
     Longleaf Partners Small-Cap Fund        I.D. No. 62-1376170
__________________________________________________________________
___________
(2)  CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP:
                                              (a)
                                              (b) X
__________________________________________________________________
___________
(3)  SEC USE ONLY
__________________________________________________________________
___________
(4)  CITIZENSHIP OR PLACE OF ORGANIZATION
     Massachusetts Business Trust
__________________________________________________________________
___________
                                   :(5) SOLE VOTING POWER
                                   :   (Discretionary Accounts)
NUMBER OF SHARES BENEFICIALLY      :       None
OWNED BY EACH REPORTING PERSON
__________________________________________
WITH                               :(6) SHARED OR NO VOTING POWER

                                         2,334,800 shares (shared)


__________________________________________
                                   :(7) SOLE DISPOSITIVE POWER

                                   :       None

__________________________________________
                                   :(8)  SHARED DISPOSITIVE POWER

                                   :    2,334,800 shares (Shared)

__________________________________________________________________
___________
(9)  AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

        2,334,800 shares
__________________________________________________________________
___________
(10)  CHECK BOX IF THE AGGREGATE AMOUNT IN ROW 9 EXCLUDES
      CERTAIN SHARES
__________________________________________________________________
___________
(11)  PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW 9
       5.4 %
__________________________________________________________________
___________
(12)  TYPE OF REPORTING PERSON
      IV
__________________________________________________________________
___________


CUSIP No. 903293405                               13G
__________________________________________________________________
___________
(1)  NAMES OF REPORTING PERSONS
     O. Mason Hawkins                         I.D. No. 257-72-3256
__________________________________________________________________
___________
(2)  CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP:
                                              (a)
                                              (b) X
__________________________________________________________________
___________
(3)  SEC USE ONLY
__________________________________________________________________
___________
(4)  CITIZENSHIP OR PLACE OF ORGANIZATION
     Citizen of United States
__________________________________________________________________
___________
                                   :(5) SOLE VOTING POWER
                                   :   (Discretionary Accounts)
NUMBER OF SHARES BENEFICIALLY      :    None
OWNED BY EACH REPORTING PERSON
__________________________________________
WITH                               :(6) SHARED VOTING POWER

                                   :    None

__________________________________________
                                   :(7) SOLE DISPOSITIVE POWER

                                   :    None

__________________________________________
                                   :(8) SHARED DISPOSITIVE POWER

                                   :    None
__________________________________________________________________
___________
(9)  AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

       None  (See Item 3 )
__________________________________________________________________
___________
(10)  CHECK BOX IF THE AGGREGATE AMOUNT IN ROW 9 EXCLUDES
      CERTAIN SHARES
__________________________________________________________________
___________
(11)  PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW 9
      0.0%
__________________________________________________________________
___________
(12)  TYPE OF REPORTING PERSON
      IN
__________________________________________________________________
___________


Item 1.

     (a). Name of Issuer: USG Corporation ("Issuer")

     (b). Address of Issuer's Principal Executive Offices:

          125 South Franklin Street; Chicago, IL 60606-4678


Item 2.

     (a) and (b). Names and Principal Business Addresses of
Persons
         Filing:

     (1)       Southeastern Asset Management, Inc.
               6410 Poplar Ave., Suite 900
               Memphis, TN 38119

     (2)  Longleaf Partners Small-Cap Fund
               c/o Southeastern Asset Management, Inc.
               6410 Poplar Avenue, Suite 900
               Memphis, TN, 38119

     (3)       Mr. O. Mason Hawkins
               Chairman of the Board and C.E.O.
               Southeastern Asset Management, Inc.
               6410 Poplar Ave., Suite 900
               Memphis, TN 38119


     (c). Citizenship:

          Southeastern Asset Management, Inc. - A Tennessee
     corporation

          Longleaf Partners Small-Cap Fund, a series of Longleaf
          Partners
          Funds Trust, a Massachusetts business trust

          Mr. O. Mason Hawkins - U.S. Citizen

     (d). Title of Class of Securities:  Common Stock (the
            "Securities").

     (e). Cusip Number: 903293405


Item 3.  If this statement is filed pursuant to Rules 13d-1 (b) or
 13d-2 (b), check whether the person filing is a:

(d.) Investment Company registered under Sec. 8 of the Investment
     Company Act - Longleaf Partners Small-Cap Fund, a series of
     Longleaf Partners Funds Trust.

(e.) Investment Adviser registered under Section 203 of the
     Investment Advisers Act of 1940.  This statement is being
filed
     by Southeastern Asset Management, Inc. as a registered
investment
     adviser. All of the securities covered by this report are
owned
     legally by Southeastern's investment advisory clients and
none
     are owned directly or indirectly by Southeastern.  As
permitted
     by Rule 13d-4, the filing of this statement shall not be
construed
     as an admission that Southeastern Asset Management, Inc. is
the
     beneficial owner of any of the securities covered by this
statement.

(g.) Parent Holding Company.  This statement is also being filed
     by
     Mr. O. Mason Hawkins, Chairman of the Board and C.E.O. of
     Southeastern Asset Management, Inc. in the event he could be
     deemed to be a controlling person of that firm as the result
of
     his official positions with or ownership of its voting
securities.
     The existence of such control is expressly disclaimed.  Mr.
Hawkins
     does not own directly or indirectly any securities covered by
     this statement for his own account.  As permitted by Rule 13d-
4,
     the filing of this statement shall not be construed as an
admission
     that Mr. Hawkins is the beneficial owner of any of the
securities
     covered by this statement.

Item 4. Ownership:

     (a). Amount Beneficially Owned: (At 8/31/02)
            3,052,700 shares

     (b). Percent of Class:
            7.1 %

          Above percentage is based on 43,250,238 shares of Common
          Stock outstanding.

     (c). Number of shares as to which such person has:

          (i).   sole power to vote or to direct the vote:

                    259,100 shares

          (ii).  shared or no power to vote or to direct the vote:

                 Shared - 2,334,800 shares.
                 Securities owned by the following series of
Longleaf
                 Partners Funds Trust, an open-end management
                 investment company registered under the
Investment
                 Company Act of 1940, as follows:

                    Longleaf Partners Small-Cap Fund - 2,334,800

                 No Power to Vote - 458,800

          (iii). sole power to dispose or to direct the
disposition
                 of:

                    717,900 shares

          (iv).  shared or no power to dispose or to direct the
                 disposition of:

                 Shared - 2,334,800 shares
                 Securities owned by the following series of
Longleaf
                 Partners Funds Trust, an open-end management
                 investment company registered under the
Investment
                 Company Act of 1940, as follows:

                    Longleaf Partners Small-Cap Fund - 2,334,800


Item 5. Ownership of Five Percent or Less of a Class:  N/A


Item 6. Ownership of More Than Five Percent on Behalf of Another
        Person:  N/A


Item 7. Identification and Classification of the Subsidiary Which
        Acquired the Security Being Reported on By the Parent
        Holding Company:  N/A


Item 8. Identification and Classification of Members of the Group:
        N/A


Item 9. Notice of Dissolution of Group:  N/A



Item 10. Certification:


By signing below I certify that, to the best of my knowledge and
belief, the securities referred to above were acquired in the
ordinary course of business and were not acquired for the purpose
and do not have the effect of changing or influencing the control
of the issuer of such securities and were not acquired in
connection with or as a participant in any transaction having such
purposes or effect.


                            Signatures

After reasonable inquiry and to the best of the knowledge and
belief of the undersigned, the undersigned certifies that the
information set forth in this statement is true, complete, and
correct.

Dated: September 6, 2002
                              Southeastern Asset Management, Inc.

                              By  /s/ Charles D. Reaves

_______________________________________________
                         Charles D. Reaves
                              Vice President and General Counsel

                         Longleaf Partners Small-Cap Fund
                         By: Southeastern Asset Management Inc.
                              /s/ Charles D. Reaves


_______________________________________________
                         Charles D. Reaves
                              Vice President & General Counsel

                              O. Mason Hawkins, Individually

                                /s/ O. Mason Hawkins

_______________________________________________

                       Joint Filing Agreement

In accordance with Rule 13d-1(f) under the Securities Exchange Act
of 1934, the persons or entities named below agree to the joint
filing on behalf of each of them of this Schedule 13G with respect
to the Securities of the Issuer and further agree that this joint
filing agreement be included as an exhibit to this Schedule 13G.
In
evidence thereof, the undersigned hereby execute this Agreement as
of September 6, 2002.
                         Southeastern Asset Management, Inc.

                              By  /s/ Charles D. Reaves

_______________________________________________
                         Charles D. Reaves
                              Vice President and General Counsel

                         Longleaf Partners Small-Cap Fund
                         By: Southeastern Asset Management, Inc.

                              /s/ Charles D. Reaves

_______________________________________________
                         Charles D. Reaves
                              Vice President & General Counsel

                              O. Mason Hawkins, Individually

                                /s/ O. Mason Hawkins

_______________________________________________