A Comparison of 122-0551 Foam Versus Vehicle Foam in Subjects With Plaque Psoriasis (Study 306)

Inclusion Criteria: * Subject has a clinical diagnosis of stable plaque psoriasis involving a minimum of 2% and no more than 12% affected body surface area. * Subject has an Investigator's Global Assessment (IGA) score of at least three (moderate) at study start. * If subject is a woman of childbearing potential, she must have a negative urine pregnancy test and agree to use an effective form of birth control for the duration of the study. Exclusion Criteria: * Subject has spontaneously improving or rapidly deteriorating plaque psoriasis. * Subject has guttate, pustular, erythrodermic or other non-plaque forms of psoriasis. * Subject has a physical condition which, in the investigator's opinion, might impair evaluation of plaque psoriasis, or which exposes the subject to an unacceptable risk by study participation. * Subject has used any phototherapy (including laser), photo-chemotherapy or other forms of photo based therapy for the treatment of their psoriasis within 30 days prior to study start. * Subject has used any systemic methotrexate, retinoids, systemic corticosteroids \[including intralesional, intra-articular, and intramuscular corticosteroids\], cyclosporine or analogous products within 90 days prior to study start. * Subject has used any systemic biologic therapy (i.e., FDA-approved or experimental therapy) within five half-lives of the biologic prior to study start. * Subject had prolonged exposure to natural or artificial sources of ultraviolet radiation within 30 days prior to study start or is intending to have such exposure during the study.