PROJECT SUMMARY In Latin America, sexual and gender minorities are disproportionately affected by HIV. Recent data from the proposed study setting of Peru suggests that the prevalence of HIV is as high as 12% among men who have sex with men (MSM) and 21% among transgender women (TGW), with >60% of new infections occurring in these key populations. Homophobia, transphobia and exaggerated masculinity (i.e., machismo) are pervasive in Latin America: one survey found that over 60% of sexual and gender minorities felt they could not disclose their sexual orientation or gender identity without fear, and 30% reported that their family was unaware of their sexual orientation. To avoid stigmatizing labels, individuals may elect not to disclose sexual or gender identity and withhold relevant information on sexual behaviors from healthcare providers. They may also incorrectly assess their own risk for important medical conditions (e.g., MPox, HIV) and opt not to engage in preventive health interventions (e.g., PrEP, HIV testing). Furthermore, the evolving terminology used to describe sexual and gender identity may vary across educational and socioeconomic status, challenging the meaningful interpretation of standardized sociodemographic surveys on sexual and gender identity. The overall goal of this proposal is to gain a better understanding of how sexual and gender identity are conceived by youth in an urban Latin American setting. We will leverage an ongoing social-behavioral intervention trial enrolling adolescents and young adults living with HIV and strong ties with the LGBTQI+ community in Lima, Peru to explore (1) how sexual identity aligns with prior consensual sexual behavior; (2) perceptions of common terms used to describe sexual and gender identity and differences according to education and socioeconomic status; and (3) reasons that sexual and gender minorities refuse, withdraw from, or have limited in engagement with healthcare, research and/or intervention activities. The findings from this research will be critical to tailoring HIV prevention messages; deriving terminology that is intuitive and aligned with the Peruvian population for patient-centered HIV care and research activities; and ensuring that that sexual and gender minorities can fully avail of existing health interventions and health research.