Exhibit 10.1

AMENDMENT TO REVOLVING CREDIT AGREEMENT

THIS AMENDMENT TO REVOLVING CREDIT AGREEMENT (this “Amendment”) is made as of March 30, 2007, by and among ERP OPERATING LIMITED PARTNERSHIP, a Delaware limited partnership (the “Borrower”), the BANKS listed on the signature pages hereof, BANK OF AMERICA, N.A., as Administrative Agent, JPMORGAN CHASE BANK, N.A., as Syndication Agent, and SUNTRUST BANK, WACHOVIA BANK, NATIONAL ASSOCIATION, WELLS FARGO BANK, N.A., LASALLE BANK NATIONAL ASSOCIATION, THE ROYAL BANK OF SCOTLAND plc, and U.S. BANK NATIONAL ASSOCIATION, as Documentation Agents.

W I T N E S S E T H:

WHEREAS, the Borrower, Administrative Agent and the Banks have entered into the Revolving Credit Agreement dated as of February 28, 2007 (the “Credit Agreement”); and

WHEREAS, the parties desire to modify the Credit Agreement upon the terms and conditions set forth herein.

NOW THEREFORE, for good and valuable consideration, the receipt and sufficiency of which are hereby acknowledged, the parties do hereby agree as follows:

1. Definitions. All capitalized terms not otherwise defined herein shall have the meanings ascribed to them in the Credit Agreement.

2. Non-Stabilized Property Value. The definition of “Non-Stabilized Property Value” is hereby deleted and the following substituted therefor:

“‘Non-Stabilized Property Value’ means, the sum of (i) the aggregate Acquisition Property Value, (ii) the aggregate Construction Property Value, (iii) the aggregate Redevelopment Property Value, (iv) the aggregate Condo Property Value, (v) the aggregate value of any Acquisition Property that was classified as a “Non-Stabilized Property” as of September 30, 2006 pursuant to the Existing Revolving Credit Agreement, valued for a period of six fiscal quarters at the greater of (1) the Property EBITDA divided by FMV Cap Rate (or Borrower’s Share thereof with respect to any such Non-Stabilized Property owned by a Consolidated Subsidiary or an Investment Affiliate), and (2) undepreciated book value (cost basis plus improvements) (or Borrower’s Share thereof with respect to any such Non-Stabilized Property owned by a Consolidated Subsidiary or an Investment Affiliate) and thereafter shall be valued as a Stabilized Property, and (vi) with respect to Raw Land or any other Non-Stabilized Property (other than the Non-Stabilized Properties described under clauses (i) through (v)), the aggregate undepreciated book value (cost basis plus improvements), determined in accordance with GAAP of such Non-Stabilized Property (or Borrower’s Share thereof with respect to any Non-Stabilized Property owned by a Consolidated Subsidiary or an Investment Affiliate). All such Acquisition Properties described under clause (v) shall be valued as a Stabilized Property following the sixth full fiscal quarter after the date of this Agreement.”

3. Effective Date. This Amendment shall become effective upon receipt by the Administrative Agent of counterparts hereof signed by the Borrower and the Required Banks (the date of such receipt being deemed the “Effective Date”).

4. Representations and Warranties. Borrower hereby represents and warrants that as of the Effective Date, all the representations and warranties set forth in the Credit Agreement, as amended hereby (other than representations and warranties which expressly speak as of a different date), are true and complete in all material respects.

5. Entire Agreement. This Amendment constitutes the entire and final agreement among the parties hereto with respect to the subject matter hereof and there are no other agreements, understandings, undertakings, representations or warranties among the parties hereto with respect to the subject matter hereof except as set forth herein.

6. Governing Law. This Amendment shall be governed by, and construed in accordance with, the law of the State of Illinois.

7. Counterparts. This Amendment may be executed in any number of counterparts, all of which taken together shall constitute one and the same agreement, and any of the parties hereto may execute this Amendment by signing any such counterpart.

8. Headings, Etc. Section or other headings contained in this Amendment are for reference purposes only and shall not in any way affect the meaning or interpretation of this Amendment.

9. No Further Modifications. Except as modified herein, all of the terms and conditions of the Credit Agreement, as modified hereby shall remain in full force and effect and, as modified hereby, the Borrower confirms and ratifies all of the terms, covenants and conditions of the Credit Agreement in all respects.

IN WITNESS WHEREOF, this Agreement has been duly executed as of the date first above written.

ERP OPERATING LIMITED PARTNERSHIP, an Illinois limited partnership

By:	Equity Residential, a Maryland real estate investment trust and its sole general partner


	By:	/s/ Donna Brandin
	Name: Donna Brandin
	Title: EVP – Chief Financial Officer

BANK OF AMERICA, N.A., as Administrative Agent and a Bank


	By:	/s/ Mark Mokelke
	Name: Mark Mokelke
	Title: Vice President

JPMORGAN CHASE BANK, N.A., as Syndication Agent and as a Bank

	By:	/s/ Marc E. Costantino
	Name: Marc E. Costantino
	Title: Executive Director

SUNTRUST BANK, as Documentation Agent
			and as a Bank


	By:	/s/ Nancy B. Richards
	Name: Nancy B. Richards
	Title: Senior Vice President

		WELLS FARGO BANK, N.A., as
		Documentation Agent and as a Bank


		By:	/s/ Scott S. Solis
			Name: Scott S. Solis
			Title: Senior Vice President

		EUROHYPO AG, NEW YORK BRANCH, as
		Managing Agent and as a Bank


		By:	/s/ Mark A. Fisher
			Name: Mark A. Fisher
			Title: Director

		By:	/s/ John Hayes
			Name: John Hayes
			Title: Vice President

		U.S. BANK NATIONAL ASSOCIATION, as
		Documentation Agent and as a Bank


		By:	/s/ Renee Lewis
			Name: Renee Lewis
			Title: Vice President

		THE ROYAL BANK OF SCOTLAND plc, as
		Documentation Agent and as a Bank

		By:	/s/ Neil Crawford
			Name: Neil Crawford
			Title: Managing Director

		CITICORP NORTH AMERICA INC., as Senior
		Managing Agent and as a Bank

		By:	/s/ Malav Kakad
			Name: Malav Kakad
			Title: Vice President

		DEUTSCHE BANK AG, NEW YORK
		BRANCH, as Senior Managing Agent and as a
		Bank

		By:	/s/ Steven P. Lapham
			Name: Steven P. Lapham
			Title: Managing Director

		By:	/s/ Joanna Soliman
			Name: Joanna Soliman
			Title: Assistant Vice President

		LEHMAN COMMERCIAL PAPER INC., as
		Senior Managing Agent and as a Bank

		By:	/s/ Janine M. Shugan
			Name: Janine M. Shugan
			Title: Authorized Signatory

		MERRILL LYNCH BANK USA, as Senior
		Managing Agent and as a Bank

		By:	/s/ Louis Alder
			Name: Louis Alder
			Title: Director

MORGAN STANLEY BANK, as Senior
Managing Agent and as a Bank

By:	/s/ Daniel Twenge
	Name: Daniel Twenge
	Title:	Authorized Signatory
		Morgan Stanley Bank

		THE BANK OF TOKYO - MITSUBISHI UFJ,
		LTD., as Co-Agent and as a Bank


		By:	/s/ James T. Taylor
			Name: James T. Taylor
			Title: Vice President

		THE BANK OF NEW YORK, as Co-Agent and
		as a Bank


		By:	/s/ Scott Detraglia
			Name: Scott Detraglia
			Title: Vice President

		COMERICA BANK, as Co-Agent and as a Bank


		By:	/s/ Leslie A. Vogel
			Name: Leslie A. Vogel
			Title: Vice President

		MEGA INTERNATIONAL COMMERCIAL
		BANK CO., LTD., NEW YORK BRANCH, as a
		Bank

		By:	/s/ Tsang-Pei Hsu
			Name: Tsang-Pei Hsu
			Title: VP & Deputy General Manager

		THE NORTHERN TRUST COMPANY, as a
		Bank

		By:	/s/ Kate M. Spadoni
			Name: Kate M. Spadoni
			Title: Second Vice President

		PEOPLE’S BANK, as a Bank

		By:	/s/ Anne Kuchinski
			Name: Anne Kuchinski
			Title: Vice President

		SUMITOMO MITSUI BANKING
		CORPORATION, as a Bank


		By:	/s/ William M. Ginn
			Name: William M. Ginn
			Title: General Manager

		FIRST HORIZON BANK, A DIVISION OF
		FIRST TENNESSEE BANK, NA, as a Bank


		By:	/s/ Kenneth W. Rub
			Name: Kenneth W. Rub
			Title: Vice President

		BANK OF CHINA, NEW YORK BRANCH, as
		a Bank

		By:	/s/ William W. Smith
			Name: William W. Smith
			Title: Deputy General Manager

BANK OF CHINA, LOS ANGELES BRANCH,
as a Bank


By:	/s/ Xiao Wang
	Name: Xiao Wang
	Title:	Branch Manager &
		First Vice President