UNITED STATES
                       SECURITIES AND EXCHANGE COMMISSION
                              WASHINGTON, DC 20549



                                    FORM 8-K


                                 CURRENT REPORT




     Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934



                Date of Report (Date of earliest event reported):
                               September 21, 2004



<TABLE>
<CAPTION>

                           Exact Name of Registrant as specified in its charter;
     Commission            State of Incorporation;                                         IRS Employer
     File Number           Address and Telephone Number                                    Identification No.
     -----------           ----------------------------                                    ------------------
    <S>                   <C>                                                                  <C>
     1-14756               Ameren Corporation                                                   43-1723446
                           (Missouri Corporation)
                           1901 Chouteau Avenue
                           St. Louis, Missouri 63103
                           (314) 621-3222

     1-2967                Union Electric Company                                               43-0559760
                           (Missouri Corporation)
                           1901 Chouteau Avenue
                           St. Louis, Missouri 63103
                           (314) 621-3222

     1-3672                Central Illinois Public Service Company                              37-0211380
                           (Illinois Corporation)
                           607 East Adams Street
                           Springfield, Illinois 62739
                           (217) 523-3600


<PAGE>

     333-56594             Ameren Energy Generating Company                                     37-1395586
                           (Illinois Corporation)
                           1901 Chouteau Avenue
                           St. Louis, Missouri 63103
                           (314) 621-3222

     2-95569               CILCORP Inc.                                                         37-1169387
                           (Illinois Corporation)
                           300 Liberty Street
                           Peoria, Illinois 61602
                           (309) 677-5230

     1-2732                Central Illinois Light Company                                       37-0211050
                           (Illinois Corporation)
                           300 Liberty Street
                           Peoria, Illinois 61602
                           (309) 677-5230


</TABLE>



     Check the  appropriate  box below if the Form 8-K  filing  is  intended  to
simultaneously  satisfy the filing obligation of the registrant under any of the
following provisions:

     [ ] Written  communications  pursuant to Rule 425 under the  Securities Act
(17 CFR 230.425)

     [ ] Soliciting  material pursuant to Rule 14a-12 under the Exchange Act (17
CFR 240.14a-12)

     [ ]  Pre-commencement  communications  pursuant to Rule 14d-2(b)  under the
Exchange Act (17 CFR 240.14d-2(b))

     [ ]  Pre-commencement  communications  pursuant to Rule 13e-4(c)  under the
Exchange Act (17 CFR 240.13e-4(c))


<PAGE>


SECTION 2 - FINANCIAL INFORMATION
ITEM 2.03.  Creation of a Direct Financial  Obligation or an Obligation under an
Off-Balance Sheet Arrangement of a Registrant.

     Reference is made to Note 4 - Short-term  Borrowings  and  Liquidity to the
financial  statements  under  Part I,  Item 1,  and to  "Liquidity  and  Capital
Resources - Short-term Borrowings and Liquidity" under "Management's  Discussion
and Analysis of Financial  Condition and Results of Operations," in Part I, Item
2, of the Registrants'  combined quarterly report on Form 10-Q for the quarterly
period  ended  June  30,  2004  for a  discussion  of  the  Registrants'  credit
facilities and credit agreement provisions.

     On September 21, 2004, Ameren Corporation  (Ameren) entered into an amended
and restated  credit  agreement with various lenders and JPMorgan Chase Bank, as
administrative agent for the lenders, which amends and restates its $235 million
three-year  revolving  credit agreement dated as of July 17, 2003 to accommodate
Ameren's  pending  acquisition of Illinois Power Company and to conform with its
two revolving credit agreements entered into in July 2004 for $700 Million.  The
amended and restated credit agreement, like the original 2003 agreement, matures
on July 17, 2006 and is to be used for  general  corporate  purposes,  including
support of commercial paper programs and the utility and the non-state regulated
subsidiary  money pool  arrangements.  The credit facility  contains  provisions
similar to those in the July 2004 credit facilities  which,  among other things,
place  restrictions  on the ability to incur  liens,  sell assets and merge with
other  entities.  It also  contains a  provision  that limits  Ameren's  and its
subsidiaries',  Central Illinois Public Service Company d/b/a AmerenCIPS,  Union
Electric   Company  d/b/a  AmerenUE,   Central   Illinois  Light  Company  d/b/a
AmerenCILCO,  and/or Illinois Power Company (from and after the date that is six
months after Ameren's acquisition of Illinois Power Company), total indebtedness
to 60% of total capitalization  pursuant to a defined calculation.  In addition,
the credit facility contains indebtedness  cross-default provisions and material
adverse  change  clauses,  similar to those  contained  in the July 2004  credit
facilities,  which could trigger a default under this facility in the event that
any of the Ameren subsidiaries (as defined),  other than certain project finance
subsidiaries,  defaults in  indebtedness  in excess of $50  million.  The credit
agreement,  like the July  2004  facilities,  also  requires  Ameren to meet the
minimum funding rules of the Employee Retirement Income Security Act of 1974, as
amended.

     Included as Exhibit 10.1 is the text of the Amended and Restated Three-Year
Revolving Credit Agreement dated as of September 21, 2004.


SECTION 9 - FINANCIAL STATEMENTS AND EXHIBITS
Item 9.01. Financial Statements and Exhibits.

     (a) Not applicable

     (b) Not applicable

     (c) Exhibits. The following exhibit is included with this Report:


                                       2
<PAGE>

     Exhibit
       No.           Description
     -------         -----------

      10.1           Amended and Restated Three-Year Revolving Credit Agreement
                     dated as of September 21, 2004.


     This combined Form 8-K is being filed separately by Ameren,  Union Electric
Company,  Central  Illinois  Public Service  Company,  Ameren Energy  Generating
Company, CILCORP Inc. and Central Illinois Light Company (each, a "registrant").
Information  contained  herein  relating to any  individual  registrant has been
filed  by  such  registrant  on  its  own  behalf.   No  registrant   makes  any
representation as to information relating to any other registrant.

                                   SIGNATURES

     Pursuant to the  requirements of the Exchange Act, each registrant has duly
caused this report to be signed on its behalf by the undersigned  thereunto duly
authorized. The signature for each undersigned company shall be deemed to relate
only to matters having reference to such company or its subsidiaries.



                                               AMEREN CORPORATION
                                                   (Registrant)

                                                   /s/ Martin J. Lyons
                                        ---------------------------------------
                                                      Martin J. Lyons
                                                 Vice President and Controller
                                                 (Principal Accounting Officer)


                                               UNION ELECTRIC COMPANY
                                                   (Registrant)

                                                   /s/ Martin J. Lyons
                                        --------------------------------------
                                                      Martin J. Lyons
                                                 Vice President and Controller
                                                 (Principal Accounting Officer)


                                       3
<PAGE>



                                        CENTRAL ILLINOIS PUBLIC SERVICE COMPANY
                                                   (Registrant)

                                                   /s/ Martin J. Lyons
                                        ----------------------------------------
                                                      Martin J. Lyons
                                                 Vice President and Controller
                                                 (Principal Accounting Officer)


                                           AMEREN ENERGY GENERATING COMPANY
                                                   (Registrant)

                                                   /s/ Martin J. Lyons
                                        ---------------------------------------
                                                      Martin J. Lyons
                                                 Vice President and Controller
                                                 (Principal Accounting Officer)


                                                   CILCORP INC.
                                                   (Registrant)

                                                   /s/ Martin J. Lyons
                                        --------------------------------------
                                                      Martin J. Lyons
                                                 Vice President and Controller
                                                 (Principal Accounting Officer)



                                             CENTRAL ILLINOIS LIGHT COMPANY
                                                   (Registrant)

                                                   /s/ Martin J. Lyons
                                        ---------------------------------------
                                                      Martin J. Lyons
                                                 Vice President and Controller
                                                 (Principal Accounting Officer)


Date:  September 21, 2004

                                       4


<PAGE>



                                  Exhibit Index
                                  -------------

Exhibit No.                       Description
-----------                       -----------

  10.1        - Amended and Restated Three-Year Revolving Credit Agreement dated
                as of September 21, 2004.
[{"type": "8-K", "sequence": "1", "filename": "ameren8k92104.txt", "description": "AMEREN8K9-21-2004", "secsgml_size_bytes": 11137}]
[{"company-data": {"conformed-name": "AMEREN CORP", "cik": "0001002910", "assigned-sic": "4931", "irs-number": "431723446", "state-of-incorporation": "MO", "fiscal-year-end": "1231"}, "filing-values": {"form-type": "8-K", "act": "34", "file-number": "001-14756", "film-number": "041039041"}, "business-address": {"street1": "1901 CHOUTEAU AVE", "street2": "MC 1370", "city": "ST LOUIS", "state": "MO", "zip": "63166-6149", "phone": "431723446"}, "mail-address": {"street1": "1901 CHOUTEAU AVE", "street2": "MC 1370", "city": "ST LOUIS", "state": "MO", "zip": "63103"}}, {"company-data": {"conformed-name": "CENTRAL ILLINOIS LIGHT CO", "cik": "0000018651", "assigned-sic": "4931", "irs-number": "370211050", "state-of-incorporation": "IL", "fiscal-year-end": "1231"}, "filing-values": {"form-type": "8-K", "act": "34", "file-number": "001-02732", "film-number": "041039042"}, "business-address": {"street1": "300 LIBERTY ST", "city": "PEORIA", "state": "IL", "zip": "61602", "phone": "3096758810"}, "mail-address": {"street1": "1901 CHOUTEAU AVE", "city": "ST. LOUIS", "state": "MO", "zip": "63103"}}, {"company-data": {"conformed-name": "CENTRAL ILLINOIS PUBLIC SERVICE CO", "cik": "0000018654", "assigned-sic": "4931", "irs-number": "370211380", "state-of-incorporation": "IL", "fiscal-year-end": "1231"}, "filing-values": {"form-type": "8-K", "act": "34", "file-number": "001-03672", "film-number": "041039045"}, "business-address": {"street1": "607 E ADAMS ST", "city": "SPRINGFIELD", "state": "IL", "zip": "62739", "phone": "3145543356"}, "mail-address": {"street1": "CENTRAL ILLINOIS PUBLIC SERVICE CO", "street2": "607 E ADAMS ST", "city": "SPRINGFIELD", "state": "IL", "zip": "62739"}}, {"company-data": {"conformed-name": "UNION ELECTRIC CO", "cik": "0000100826", "assigned-sic": "4911", "irs-number": "430559760", "state-of-incorporation": "MO", "fiscal-year-end": "1231"}, "filing-values": {"form-type": "8-K", "act": "34", "file-number": "001-02967", "film-number": "041039046"}, "business-address": {"street1": "1901 CHOUTEAU AVENUE", "street2": "MC 1370", "city": "ST LOUIS", "state": "MO", "zip": "63166", "phone": "314-554-3356"}, "mail-address": {"street1": "1901 CHOUTEAU AVENUE", "street2": "MC 1370", "city": "ST LOUIS", "state": "MO", "zip": "63166"}}, {"company-data": {"conformed-name": "CILCORP INC", "cik": "0000762129", "assigned-sic": "4931", "irs-number": "371169387", "state-of-incorporation": "IL", "fiscal-year-end": "1231"}, "filing-values": {"form-type": "8-K", "act": "34", "file-number": "002-95569", "film-number": "041039043"}, "business-address": {"street1": "300 LIBERTY ST", "street2": "STE 300", "city": "PEORIA", "state": "IL", "zip": "61602", "phone": "3145543356"}, "mail-address": {"street1": "1901 CHOUTEAU AVE MC-1370", "city": "ST. LOUIS", "state": "MO", "zip": "63103"}}, {"company-data": {"conformed-name": "AMERENENERGY GENERATING CO", "cik": "0001135361", "assigned-sic": "4911", "irs-number": "371395586", "state-of-incorporation": "IL", "fiscal-year-end": "1231"}, "filing-values": {"form-type": "8-K", "act": "34", "file-number": "333-56594", "film-number": "041039044"}, "business-address": {"street1": "1901 CHOUTEAU AVENUE", "city": "ST LOUIS", "state": "MO", "zip": "63103", "phone": "3145543922"}, "mail-address": {"street1": "1901 CHOUTEAU AVENUE", "city": "ST LOUIS", "state": "MO", "zip": "63103"}}]
UNITED STATES
                       SECURITIES AND EXCHANGE COMMISSION
                              WASHINGTON, DC 20549

                                    FORM 8-K

                                 CURRENT REPORT

     Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934

                Date of Report (Date of earliest event reported):
                               September 21, 2004
Exact Name of Registrant as specified in its charter;
     Commission            State of Incorporation;                                         IRS Employer
     File Number           Address and Telephone Number                                    Identification No.
     -----------           ----------------------------                                    ------------------
1-14756               Ameren Corporation                                                   43-1723446
                           (Missouri Corporation)
                           1901 Chouteau Avenue
                           St. Louis, Missouri 63103
                           (314) 621-3222

     1-2967                Union Electric Company                                               43-0559760
                           (Missouri Corporation)
                           1901 Chouteau Avenue
                           St. Louis, Missouri 63103
                           (314) 621-3222

     1-3672                Central Illinois Public Service Company                              37-0211380
                           (Illinois Corporation)
                           607 East Adams Street
                           Springfield, Illinois 62739
                           (217) 523-3600
333-56594             Ameren Energy Generating Company                                     37-1395586
                           (Illinois Corporation)
                           1901 Chouteau Avenue
                           St. Louis, Missouri 63103
                           (314) 621-3222

     2-95569               CILCORP Inc.                                                         37-1169387
                           (Illinois Corporation)
                           300 Liberty Street
                           Peoria, Illinois 61602
                           (309) 677-5230

     1-2732                Central Illinois Light Company                                       37-0211050
                           (Illinois Corporation)
                           300 Liberty Street
                           Peoria, Illinois 61602
                           (309) 677-5230
Check the  appropriate  box below if the Form 8-K  filing  is  intended  to
simultaneously  satisfy the filing obligation of the registrant under any of the
following provisions:

     [ ] Written  communications  pursuant to Rule 425 under the  Securities Act
(17 CFR 230.425)

     [ ] Soliciting  material pursuant to Rule 14a-12 under the Exchange Act (17
CFR 240.14a-12)

     [ ]  Pre-commencement  communications  pursuant to Rule 14d-2(b)  under the
Exchange Act (17 CFR 240.14d-2(b))

     [ ]  Pre-commencement  communications  pursuant to Rule 13e-4(c)  under the
Exchange Act (17 CFR 240.13e-4(c))
SECTION 2 - FINANCIAL INFORMATION
ITEM 2.03.  Creation of a Direct Financial  Obligation or an Obligation under an
Off-Balance Sheet Arrangement of a Registrant.

     Reference is made to Note 4 - Short-term  Borrowings  and  Liquidity to the
financial  statements  under  Part I,  Item 1,  and to  "Liquidity  and  Capital
Resources - Short-term Borrowings and Liquidity" under "Management's  Discussion
and Analysis of Financial  Condition and Results of Operations," in Part I, Item
2, of the Registrants'  combined quarterly report on Form 10-Q for the quarterly
period  ended  June  30,  2004  for a  discussion  of  the  Registrants'  credit
facilities and credit agreement provisions.

     On September 21, 2004, Ameren Corporation  (Ameren) entered into an amended
and restated  credit  agreement with various lenders and JPMorgan Chase Bank, as
administrative agent for the lenders, which amends and restates its $235 million
three-year  revolving  credit agreement dated as of July 17, 2003 to accommodate
Ameren's  pending  acquisition of Illinois Power Company and to conform with its
two revolving credit agreements entered into in July 2004 for $700 Million.  The
amended and restated credit agreement, like the original 2003 agreement, matures
on July 17, 2006 and is to be used for  general  corporate  purposes,  including
support of commercial paper programs and the utility and the non-state regulated
subsidiary  money pool  arrangements.  The credit facility  contains  provisions
similar to those in the July 2004 credit facilities  which,  among other things,
place  restrictions  on the ability to incur  liens,  sell assets and merge with
other  entities.  It also  contains a  provision  that limits  Ameren's  and its
subsidiaries',  Central Illinois Public Service Company d/b/a AmerenCIPS,  Union
Electric   Company  d/b/a  AmerenUE,   Central   Illinois  Light  Company  d/b/a
AmerenCILCO,  and/or Illinois Power Company (from and after the date that is six
months after Ameren's acquisition of Illinois Power Company), total indebtedness
to 60% of total capitalization  pursuant to a defined calculation.  In addition,
the credit facility contains indebtedness  cross-default provisions and material
adverse  change  clauses,  similar to those  contained  in the July 2004  credit
facilities,  which could trigger a default under this facility in the event that
any of the Ameren subsidiaries (as defined),  other than certain project finance
subsidiaries,  defaults in  indebtedness  in excess of $50  million.  The credit
agreement,  like the July  2004  facilities,  also  requires  Ameren to meet the
minimum funding rules of the Employee Retirement Income Security Act of 1974, as
amended.

     Included as Exhibit 10.1 is the text of the Amended and Restated Three-Year
Revolving Credit Agreement dated as of September 21, 2004.

SECTION 9 - FINANCIAL STATEMENTS AND EXHIBITS
Item 9.01. Financial Statements and Exhibits.

     (a) Not applicable

     (b) Not applicable

     (c) Exhibits. The following exhibit is included with this Report:

                                       2
Exhibit
       No.           Description
     -------         -----------

      10.1           Amended and Restated Three-Year Revolving Credit Agreement
                     dated as of September 21, 2004.

     This combined Form 8-K is being filed separately by Ameren,  Union Electric
Company,  Central  Illinois  Public Service  Company,  Ameren Energy  Generating
Company, CILCORP Inc. and Central Illinois Light Company (each, a "registrant").
Information  contained  herein  relating to any  individual  registrant has been
filed  by  such  registrant  on  its  own  behalf.   No  registrant   makes  any
representation as to information relating to any other registrant.

                                   SIGNATURES

     Pursuant to the  requirements of the Exchange Act, each registrant has duly
caused this report to be signed on its behalf by the undersigned  thereunto duly
authorized. The signature for each undersigned company shall be deemed to relate
only to matters having reference to such company or its subsidiaries.

                                               AMEREN CORPORATION
                                                   (Registrant)

                                                   /s/ Martin J. Lyons
                                        ---------------------------------------
                                                      Martin J. Lyons
                                                 Vice President and Controller
                                                 (Principal Accounting Officer)

                                               UNION ELECTRIC COMPANY
                                                   (Registrant)

                                                   /s/ Martin J. Lyons
                                        --------------------------------------
                                                      Martin J. Lyons
                                                 Vice President and Controller
                                                 (Principal Accounting Officer)

                                       3
CENTRAL ILLINOIS PUBLIC SERVICE COMPANY
                                                   (Registrant)

                                                   /s/ Martin J. Lyons
                                        ----------------------------------------
                                                      Martin J. Lyons
                                                 Vice President and Controller
                                                 (Principal Accounting Officer)

                                           AMEREN ENERGY GENERATING COMPANY
                                                   (Registrant)

                                                   /s/ Martin J. Lyons
                                        ---------------------------------------
                                                      Martin J. Lyons
                                                 Vice President and Controller
                                                 (Principal Accounting Officer)

                                                   CILCORP INC.
                                                   (Registrant)

                                                   /s/ Martin J. Lyons
                                        --------------------------------------
                                                      Martin J. Lyons
                                                 Vice President and Controller
                                                 (Principal Accounting Officer)

                                             CENTRAL ILLINOIS LIGHT COMPANY
                                                   (Registrant)

                                                   /s/ Martin J. Lyons
                                        ---------------------------------------
                                                      Martin J. Lyons
                                                 Vice President and Controller
                                                 (Principal Accounting Officer)

Date:  September 21, 2004

                                       4
Exhibit Index
                                  -------------

Exhibit No.                       Description
-----------                       -----------

  10.1        - Amended and Restated Three-Year Revolving Credit Agreement dated
                as of September 21, 2004.