This article presents a three-module intervention based on social action theory that focuses on health promotion and social identity formation for seropositive youth. The modules are designed to reduce transmission of HIV by reducing sexual and substance abuse acts, increasing healthy acts and adherence to care, and maintaining positive behavioral routines. Components of the modules are described, including examples of how these components are implemented in the actual intervention sessions. The importance of using successive approximation to consolidate changes in behavior by defining social roles and personal identities that are consistent with positive behavioral routines is demonstrated. Outcomes of the intervention are presented as well as issues of cost-effectiveness, feasibility, and alternative implementation strategies.