 The purpose of this study is to determine the effect of etanercept 50 mg twice weekly compared to placebo over 12 weeks on the psoriasis area and severity index PASI in subjects with psoriasis. This study will also evaluate the safety and tolerability of etanercept 50 mg twice weekly; determine the effect of etanercept 50 mg twice weekly on patient reported outcomes PRO; and characterize the pharmacokinetics PK profile of etanercept 50 mg twice weekly. 