TW in Peru are at high risk for HIV infection (30-33% HIV prevalence) and in urgent need of new approaches to prevention that adequately address HIV risk as part of their life contexts. Due to their social and economic marginalization and lack of support from traditional neighborhood and family networks, TW frequently neglect traditional approaches to HIV/STI prevention that have been developed for men who have sex with men (MSM), and report high rates of compensated sex, unprotected intercourse, and sexually transmitted infection (STI) co-infections. Despite their socially marginalized status, communities of TW in Lima are frequently connected through dense social and geographic networks that provide support outside of traditional community systems, disseminate new information and ideas, and define and maintain standards of behavior. While these social networks provide a critical framework for the dissemination and maintenance of TW community norms, they have not previously been used as a framework for HIV prevention.