Exhibit 12

ERP OPERATING LIMITED PARTNERSHIP

Computation of Ratio of Earnings to Combined Fixed Charges

	06/30/04			06/30/03		12/31/03		12/31/02		12/31/01		12/31/00		12/31/99
Income from continuing operations	$		110,668	$	123,233	$	236,150	$	261,762	$	321,309	$	287,221	$	240,364
Interest expense incurred, net	166,338			162,380		325,191		331,489		342,712		354,916		316,875
Amortization of deferred financing costs	3,127			2,897		6,081		5,587		4,912		4,959		3,797
Earnings before combined fixed charges and preferred distributions	280,133			288,510		567,422		598,838		668,933		647,096		561,036
Preferred distributions	37,493			48,417		96,971		97,151		106,119		111,941		113,196
Premium on redemption of preference units	—			—		20,237		—		5,324		—		—
Earnings before combined fixed charges	$	242,640		$	240,093	$	450,214	$	501,687	$	557,490	$	535,155	$	447,840
Interest expense incurred, net	$	166,338		$	162,380	$	325,191	$	331,489	$	342,712	$	354,916	$	316,875
Amortization of deferred financing costs	3,127			2,897		6,081		5,587		4,912		4,959		3,797
Interest capitalized for real estate and unconsolidated entities under development	6,850			10,923		20,647		27,167		28,174		17,650		8,134
Total combined fixed charges	176,315			176,200		351,919		364,243		375,798		377,525		328,806
Preferred distributions	37,493			48,417		96,971		97,151		106,119		111,941		113,196
Premium on redemption of preference units	—			—		20,237		—		5,324		—		—
Total combined fixed charges and preferred distributions	$	213,808		$	224,617	$	469,127	$	461,394	$	487,241	$	489,466	$	442,002
Ratio of earnings before combined fixed charges to total combined fixed charges	1.38			1.36		1.28		1.38		1.48		1.42		1.36
Ratio of earnings before combined fixed charges and preferred distributions to total combined fixed charges and preferred distributions	1.31			1.28		1.21		1.30		1.37		1.32		1.27