This article presents the results of a systematic review of the effectiveness and economic efficiency of individual-, group-, and community-level behavioral interventions intended to reduce the risk of acquiring sexually transmitted HIV in adult men who have sex with men (MSM). These results form the basis for recommendations by the Task Force on Community Preventive Services on the use of these interventions. Sexual risk behavior and condom use were the outcomes used to assess effectiveness. Intervention effectiveness on biological outcomes could not be assessed because too few studies of adequate quality have been published.