Psoriasis is an immune-mediated skin disease in which chronic T-cell stimulation by antigen-presenting cells (APC) occurs in the skin. This interplay between the T-cell and APC has been likened to a "T-AP dance" where specific steps must occur in sequence to result in T-cell activation and the disease phenotype; otherwise T-cell anergy would occur. Several novel engineered proteins designed to block specific steps in immune activation (biologic agents) have demonstrated efficacy in the treatment of psoriasis. These agents include fusion proteins, monoclonal antibodies and recombinant cytokines. These medications act at specific steps during the T-AP dance either to inhibit T-cell activation, costimulation and subsequent proliferation of T-cells, lead to immune deviation or induce specific cytokine blockades. The potential increased selectivity for specific pathways in immune activation, clinical efficacy and relative safety of these new agents offers an alternative for the treatment of moderate to severe psoriasis.