EXHIBIT 10.56.1

     AMENDMENT NO. 1, dated as of May 27, 1999 (this "Amendment"), to the
Guarantee and Collateral Agreement, dated as of March 18, 1999 (the
"AGREEMENT"), among (i) EDISON MISSION HOLDINGS CO ., a California corporation
(the "BORROWER"), (ii) EDISON MISSION FINANCE CO., a California corporation
("Edison Mission Finance"), (iii) HOMER CITY PROPERTY HOLDINGS, INC., a
California corporation ("HOMER CITY HOLDINGS"), (iv) CHESTNUT RIDGE ENERGY
COMPANY, a California corporation ("CHESTNUT RIDGE"), (v) MISSION ENERGY
WESTSIDE, INC., a California corporation ("MEW"), (vi)EME HOMER CITY GENERATION
L.P., a Pennsylvania limited partnership ("EME HOMER CITY"), (vii) EDISON
MISSION ENERGY, a California corporation ("EDISON MISSION ENERGY"); and,
together with the Borrower, Edison Mission Finance, Homer City Holdings,
Chestnut Ridge, MEW and EME Homer City, the "GRANTORS"), and (viii) UNITED
STATES TRUST COMPANY OF NEW YORK, as collateral agent for the Secured Parties
(in such capacity, the "COLLATERAL AGENT").

                                    RECITALS

          A. The Borrower has entered into a Credit Agreement, dated as of March
18, 1999 (as the same may be amended, supplemented or otherwise modified from
time to time, the "CREDIT AGREEMENT"; the loans made thereunder, the "LOANS"),
with certain financial institutions (collectively, the "LENDERS") and Citicorp
USA, Inc., as administrative agent for the Lenders (in such capacity, the
"ADMINISTRATIVE AGENT").

          B. Pursuant to the Agreement, each Grantor pledged and assigned to the
Collateral Agent for the benefit of the Secured Parties security interests in
certain personal property of such Grantor described in the Agreement.

          C. The Borrower wished to issue $300 million in aggregate principal
amount of Senior Secured Bonds due 2019 and $530 million in aggregate principal
amount of Senior Secured Bonds due 2026 (collectively, the "BONDS"; the trustee
to the holders thereof, the "TRUSTEE"), the proceeds of which will be used to
refinance a portion of the Loans and to repay a portion of the Borrower's direct
parent's equity investment in the Borrower.

          D. The Grantors have requested, and, upon this Amendment becoming
effective, the Collateral Agent has agreed, that certain provisions of the
Agreement be amended in the manner provided for in this Amendment.


         NOW, THEREFORE, the parties hereto hereby agree as follows:

         1. DEFINITION OF SECURED PARTIES. The definition of "Secured Parties"
in Section 1.1(b) of the Agreement is hereby amended by adding the phrase "the
Trustee," after the phrase "the Lenders," in the first line of such
definition.

         2. GRANT AND CONFIRMATION OF GRANT OF SECURITY INTEREST. Each of the
Grantors hereby grants and confirms the grant of the security interest in the
Collateral in favor of the Collateral Agent for the benefit of the Secured
Parties (as defined in this Amendment) to secure such Grantor's Obligations.
Edison Mission Energy hereby grants and confirms the grant of the security
interest in all shares of capital stock of the Borrower in favor of the
Collateral Agent for the benefit of the Secured Parties (as defined in this
Amendment) to secure the Borrower Obligations.

         3. COUNTERPARTS. This Amendment may be executed by the parties
hereto in any number of separate counterparts, and all of said counterparts
taken together shall be deemed to constitute one and the same instrument.
Delivery of an executed counterpart of a signature page to this letter by
facsimile shall be effective as delivery of a manually executed counterpart
of this Amendment.

         4. LIMITED EFFECT. Except as expressly provided herein, all of the
terms and provisions of the Agreement are and shall remain in full force and
effect.

         5. SEVERABILITY. Any provision of this Amendment which is prohibited
or unenforceable in any jurisdiction shall, as to such jurisdiction, be
ineffective to the extent of such prohibition or unenforceability without
invalidating the remaining provisions hereof, and any such prohibition or
unenforceability in any jurisdiction shall not invalidate or render
unenforceable such provision in any other jurisdiction.

         6. CONDITIONS TO EFFECTIVENESS. The amendment provided for herein
shall become effective on the date the Collateral Agent shall have received
counterparts of this Amendment duly executed and delivered by each Grantor
and consented to by the Administrative Agent and the Trustee.

         7. APPLICABLE LAW. THIS AMENDMENT AND THE RIGHTS AND OBLIGATIONS OF
THE PARTIES HERETO SHALL BE GOVERNED BY, AND CONSTRUED AND INTERPRETED IN
ACCORDANCE WITH, THE LAWS OF THE STATE OF NEW YORK.

                                      2





                                          MISSION ENERGY WESTSIDE, INC.



                                          By:  /s/ Steven D. Eisenberg
                                             ----------------------------
                                             Name: Steven D. Eisenberg
                                             Title: Vice President



                                          EME HOMER CITY GENERATION L.P.
                                          By: Mission Energy Westside,  Inc.
                                              its General Partner


                                          By:  /s/ Steven D. Eisenberg
                                             ----------------------------
                                             Name: Steven D. Eisenberg
                                             Title: Vice President



                                          EDISON MISSION ENERGY



                                          By:  /s/ Steven D. Eisenberg
                                             ----------------------------
                                             Name: Steven D. Eisenberg
                                             Title: Vice President



                                          UNITED STATES TRUST COMPANY OF
                                          NEW YORK, as Collateral Agent


                                          By:  /s/ Christopher J. Grell
                                             ----------------------------
                                             Name: Christopher J. Grell
                                             Title: Assistant Vice President


    Signature Page to Amendment No. 1 to Guarantee and Collateral Agreement



     IN WITNESS WHEREOF, the parties hereto have caused this Amendment to be
duly executed and delivered by their respective proper and duly authorized
officers as of the day and year first above written.


                                          EDISON MISSION HOLDINGS CO.



                                          By:  /s/ Steven D. Eisenberg
                                             ----------------------------
                                             Name: Steven D. Eisenberg
                                             Title: Vice President



                                          EDISON MISSION FINANCE CO.



                                          By:  /s/ Steven D. Eisenberg
                                             ----------------------------
                                             Name: Steven D. Eisenberg
                                             Title: Vice President



                                          HOMER CITY PROPERTY HOLDINGS,
                                          INC.



                                          By:  /s/ Steven D. Eisenberg
                                             ----------------------------
                                             Name: Steven D. Eisenberg
                                             Title: Vice President



                                          CHESTNUT RIDGE ENERGY COMPANY



                                          By:  /s/ Steven D. Eisenberg
                                             ----------------------------
                                             Name: Steven D. Eisenberg
                                             Title: Vice President


    Signature Page to Amendment No. 1 to Guarantee and Collateral Agreement





Acknowledged and Consented to by:


CITICORP USA, INC., as Administrative Agent


By:  /s/ Anita J. Brickell
   ---------------------------------
   Name: Anita J. Brickell
   Title: Managing Director



UNITED STATES TRUST COMPANY OF NEW YORK, as Trustee


By:  /s/ Christopher J. Grell
   ---------------------------------
   Name: Christopher J. Grell
   Title: Assistant Vice President



    Signature Page to Amendment No. 1 to Guarantee and Collateral Agreement