A Study Evaluating The Efficacy And Safety Of CP-690,550 In Asian Subjects With Moderate To Severe Plaque Psoriasis

Inclusion Criteria: * Have had a diagnosis of plaque-type psoriasis (psoriasis vulgaris) for at least 12 months prior to the first screening procedure. * Have a PASI score of 12 or greater AND a PGA score of 3 ("moderate") or 4 ("severe") at Baseline (Day 1). * Considered by dermatologist investigator to be a candidate for systemic therapy or phototherapy of psoriasis (either naïve or history of previous treatment). Exclusion Criteria: * Currently have non-plaque forms of psoriasis, eg, erythrodermic, guttate, or pustular psoriasis, with the exception of nail psoriasis which is allowed. * Have current drug induced psoriasis, eg, a new onset of psoriasis or an exacerbation of psoriasis from beta blockers, calcium channel blockers, antimalarial drugs or lithium. * Subjects who cannot discontinue systemic therapies and/or topical therapies for the treatment of psoriasis and cannot discontinue phototherapy (UVB or PUVA) for the study are excluded.