The mechanisms of cutaneous lupus erythematosus are under active investigation, and important advances have been made. Humoral mechanisms are likely important in subacute cutaneous lupus erythematosus, the cutaneous subset most associated with the Ro antibody. Many advances have been made in understanding the various Ro epitopes and the specificities of the Ro antibody response. Lupus mice experiments have provided insight into the contributing roles of various T-cell subsets. Variations in cytokine production related to genetic polymorphisms and induction by ultraviolet light combined with alterations in selectins and adhesion molecules contribute to the accumulation of inflammatory cells in cutaneous lupus erythematosus. It is important to institute aggressive systemic therapy when there is widespread scarring disease. Antimalarial agents continue to be first-line systemic drugs, and our understanding of the use of combination antimalarial agents and proper dosing limits problems with toxicity and improves efficacy. Other therapies, including thalidomide, are helpful for patients with resistant disease.