 Inclusion Criteria: - Stable, active plaque psoriasis involving greater than or equal to 10 of body surface area BSA at screening and baseline Exclusion Criteria: - Any grade 3 or 4 adverse event or infection within 28 days before screening, or between the screening visit and study drug initiation - Evidence of skin conditions e.g., eczema other than psoriasis that would interfere with evaluations of the effect of study medication on psoriasis - Psoralen plus ultraviolet A radiation PUVA, oral retinoids, cyclosporine, alefacept Amevive, efalizumab Raptiva, or any other systemic anti-psoriasis therapy within 28 days of study drug initiation - Ultraviolet light B UVB therapy, topical steroids, topical vitamin A or D analog preparations, or anthralin within 14 days of study drug initiation exception: topical steroids, at no higher than moderate strength, are permitted on scalp, axillae, and groin but dose and formulation must remain stable throughout trial - Prior exposure to any tumor necrosis factor TNF-inhibitor, including etanercept - Severe comorbidities - Known history of tuberculosis TB, or previous positive purified protein derivative PPD test 