Exhibit 10.3
PLEDGE AGREEMENT SUPPLEMENT

PLEDGE AGREEMENT SUPPLEMENT dated as of July 14, 2006 (this "Supplement") made
by CILCORP, Inc., an Illinois corporation (the "Pledgor"), in favor of The Bank
of New York, a New York banking corporation, as collateral agent (in such
capacity, the "Collateral Agent") for the benefit of the Secured Parties (as
defined in the Pledge Agreement referred to below).
 
1.  This Supplement is executed and delivered pursuant to the terms of the
Pledge Agreement, dated as of October 18, 1999 (as supplemented by this
Supplement and as the same has been and may hereafter be supplemented by any
other Pledge Agreement Supplement or otherwise amended or modified, the "Pledge
Agreement"), made by the Pledgor in favor of the Collateral Agent for the
benefit of the Collateral Agent and the Secured Parties. Terms defined in the
Pledge Agreement are used herein with their defined meanings.
 
2.  Pursuant to the terms of the Indenture and the Pledge Agreement, the Pledgor
may incur additional secured indebtedness from time to time that is by its terms
equally and ratably secured under the Pledge Agreement with the Obligations
secured thereunder. The Pledgor, Central Illinois Public Service Company,
Illinois Power Company, Central Illinois Light Company and AmerenEnergy
Resources Generating Company, as Borrowers, JPMorgan Chase Bank, N.A., as
Administrative Agent (the "Agent"), and the Lenders from time to time party
thereto (the "Lenders") have entered into that certain Senior Secured Revolving
Credit Agreement (the "Credit Agreement"), dated as of July 14, 2006, pursuant
to which the Pledgor may initially borrow and/or request the issuance of letters
of credit in an aggregate principal amount or face amount up to $50 million. The
terms of the Credit Agreement require that the Pledgor equally and ratably
secure its obligations in respect of the principal of and interest on any and
all loans to the Pledgor under the Credit Agreement, all reimbursement
obligations in respect of letters of credit issued pursuant to the Credit
Agreement for the account of the Pledgor and all other "Obligations" (as defined
in the Credit Agreement) of the Pledgor (the "Credit Agreement Obligations")
with the Obligations secured under the Pledge Agreement. The Pledgor hereby
acknowledges and agrees that the Credit Agreement Obligations shall be deemed to
be "Additional Debt Obligations" pursuant to the Pledge Agreement.
 
3.  The Pledgor confirms and reaffirms the security interest in the Collateral
granted to the Collateral Agent, for the benefit of the Collateral Agent and the
Secured Parties under the Pledge Agreement; and hereby acknowledges and agrees
that all references to "Secured Parties" in the Pledge Agreement shall be deemed
to include all holders of the Additional Secured Debt as described on Schedule I
hereto.
 
4.  The Pledgor hereby represents and warrants that the representations and
warranties contained in Section 3 of the Pledge Agreement are true and correct
on the date of this Supplement with all references therein and elsewhere in the
Pledge Agreement to "Additional Secured Debt", "Additional Debtholders" and
"Additional Secured Debt Agent" to include the Additional Secured Debt,
Additional Debtholders and Additional Secured Debt Agent as listed on Schedule I
hereto and on Schedule I to each Pledge Agreement Supplement executed prior to
the date hereof and with references therein to "this Pledge Agreement" to mean
the Pledge
 

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Agreement as supplemented hereby; provided that such representations and
warranties of the Pledge Agreement shall hereafter be deemed to provide that (i)
the Pledged Shares constitute all of the issued and outstanding common stock of
CILCO and all the other capital stock of CILCO held by the Pledgor and (ii) the
exercise by the Collateral Agent of the voting or other rights provided for in
the Pledge Agreement or the remedies in respect of the Collateral pursuant to
the Pledge Agreement may be subject to receipt of regulatory approvals under
laws applicable to the change in control of a public utility company. In
addition, the Pledgor represents and warrants that this Supplement has been duly
executed and delivered by the Pledgor and constitutes a legal, valid and binding
obligation of the Pledgor enforceable against the Pledgor in accordance with its
terms, except as may be limited by applicable bankruptcy, insolvency,
reorganization, fraudulent conveyance, moratorium or similar laws affecting the
enforcement of creditors' rights and remedies generally and by equitable
principles of general applicability.
 
5.  The Additional Debtholders designated on Schedule I hereto, by their
acceptance of the benefits of the Pledge Agreement, hereby irrevocably designate
the Collateral Agent to act on their behalf as specified in the Pledge
Agreement. Each such Additional Debtholder hereby irrevocably authorizes, and
each holder of the Additional Debt Obligations by the acceptance of such
Additional Debt Obligation and by the acceptance of the benefits of the Pledge
Agreement shall be deemed irrevocably to authorize the Collateral Agent to take
such action on its behalf under the Pledge Agreement and instruments and
agreements referred to therein and to exercise such powers and to perform such
duties thereunder as are specifically delegated or required of the Collateral
Agent by the terms thereof and such other powers as are reasonably incident
thereto.
 
6.  This Supplement is supplemental to the Pledge Agreement, forms a part
thereof and is subject to all the terms thereof. Schedule I to the Pledge
Agreement does, and shall be deemed to, include each item listed on Schedule I
hereto, and each such item shall be and is included within the meaning of the
terms "Additional Secured Debt", "Additional Debtholders" and "Additional
Secured Debt Agent" as such terms are used in the Pledge Agreement.

 
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IN WITNESS WHEREOF, the Pledgor has caused this Supplement to be duly executed
and delivered on the date first set forth above.
 
CILCORP INC.

By:  /s/ Jerre E. Birdsong                        
Name:  Jerre E. Birdsong
Title:    Vice President and Treasurer
Acknowledged and agreed:

THE BANK OF NEW YORK,
as Collateral Agent

By: /s/ Robert A. Massimillo           
Name:  Robert A. Massimillo    
Title:    Vice President    
 
CILCORP PLEDGE AGREEMENT SUPPLEMENT
SIGNATURE PAGE

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JPMorgan Chase Bank, N.A., as Administrative Agent
under the Credit Agreement, on behalf of itself and the Lenders

By:  /a/ Michael J. DeForge         
Name:  Michael J. DeForge    
Title:    Vice President    
 
CILCORP PLEDGE AGREEMENT SUPPLEMENT
SIGNATURE PAGE

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Schedule I
to Pledge Agreement Supplement

ADDITIONAL SECURED DEBT

Title or Name of Additional Secured Debt
 
 
Additional Debtholders
 
Additional Secured Debt
Agent
"Obligations", as defined in the Senior
Secured Revolving Credit Agreement dated
as of July 14, 2006 (the "Credit Agreement")
among CILCORP, Inc., Central Illinois
Public Service Company, Illinois Power
Company, Central Illinois Light Company
and AmerenEnergy Resources Generating,
Inc., as Borrowers, the Lenders from time to
time part thereto and JPMorgan Chase Bank,
N.A., as Administrative Agent
 
The Lenders from time
to time party to the
Credit Agreement
 
JPMorgan Chase Bank,
N.A., as Administrative
Agent