Project Summary/Abstract Latinos comprise 19% of the population in the United States, yet represent 29% of new HIV infections in the United States. Pre-exposure prophylaxis (PrEP) is one the most important biomedical preventions interventions currently available and provides up to 99% protection against HIV infection.[3] Access and use of PrEP is inconsistent among LSMM. Viral suppression remains elusive among LSMM living with HIV. LSMM also report high rates of psychologic symptoms of distress. These disparities are exacerbated by poverty, systemic racism, and homophobia We know little about the effect that families have on the long-term health outcomes of LSMM. Longitudinal studies of LSMM can help answer important questions about critical upstream entry points for intervening on HIV and mental health outcomes. We propose the following aims: Aim 1: To determine how family ties affect mental health outcomes and HIV-related behaviors (e.g., substance use, condomless sex) and HIV treatment (e.g., HIV viral load) of LSMM over time. We will analyze data on family support, depressive symptoms, HIV-related behaviors, and treatment outcomes in mSTUDY, a NIDA-funded cohort study of diverse MSM in Los Angeles. It has collected detailed psychosocial, behavioral, and biological assessments every six months since 2013. Hypothesis 1: LSMM with greater family emotional support will report fewer depressive symptoms and HIV-related risk behaviors and better treatment outcomes than LSMM who report less family emotional support. Aim 2: Determine whether family support and experiences of discrimination affect changes in the behaviors, mental health, and health of LSMM. We will analyze data on family support, depressive symptoms, HIV-related behaviors, and treatment outcomes in a randomly selected cohort of 250 Latino men every six months for 5 years and in mSTUDY. Hypothesis 2A: Increased family support and decreased experiences of discrimination will lead to a reduction in risk behaviors and to improved mental and physical health outcomes. Hypothesis 2B: The association between experiences of discrimination with HIV-related behaviors, mental health, and health outcomes will be weaker in Latino men with high levels of family support. Hypothesis 2C: The association between family support and experiences of discrimination with LSMM’s physical health and mental health is mediated by LSMM’s behaviors. Aim 3: Identify culturally specific strategies to integrate families into HIV prevention and treatment. We will interview diverse LSMM and conduct focus group with families in Los Angeles, New York, and Miami to develop strategies for service providers to integrate family members into HIV biomedical interventions. The results will enable us to assess LSMM health nationally and obtain their input into how to design and support family-based interventions to increase health behaviors and improve health outcomes for LSMM.