An individualized treatment regimen is necessary for each patient with psoriasis because of the diverse nature of the disease. The manifestation of psoriasis, the severity and extent of the lesions, and the medical history and lifestyle of the patient are important factors that determine the selection of treatment, but in general therapies with the fewest side effects are preferred. First-line topical treatments are corticosteroids, calcipotriene, and tazarotene. If topical treatments are unsuccessful, phototherapy with ultraviolet B or photochemotherapy with psoralens plus ultraviolet A (PUVA) are the next choices. If psoriasis fails to respond to an adequate trial of topical therapy or phototherapy, systemic therapies including methotrexate, acitretin, or cyclosporin should be initiated. Because the regimens involved in systemic and phototherapy are complex and require frequent dose adjustments and specialized equipment, the patient should be referred to a dermatologist when topical therapy is not effective.