This article contains a comprehensive, critical review of the acquired immunodeficiency syndrome (AIDS)-risk-reduction literature on interventions that have targeted risky sexual behavior and intravenous drug use practices. A conceptually based, highly generalizable model for promoting and evaluating AIDS-risk behavior change in any population of interest is then proposed. The model holds that AIDS-risk reduction is a function of people's information about AIDS transmission and prevention, their motivation to reduce AIDS risk, and their behavioral skills for performing the specific acts involved in risk reduction. Supportive tests of this model, using structural equation modeling techniques, are then reported for populations of university students and gay male affinity group members.