This application requests support and training for a New/Early Stage Investigator in research independence to conduct HIV and substance use prevention research. The PI and mentorship team will explore sexual identity, sexual identity disclosure, and minority stress as it relates to pre-exposure prophylaxis (PrEP) linkage to care and substance use experiences among African American and Hispanic/Latino young men who have sex with men (AA/HL YMSM). Substance use compounds HIV risk and disrupts the PrEP care continuum. This proposal is focused on AA/HL YMSM because of the high incidence of HIV infection among these populations and disproportionately high rates of substance use. PrEP is a key approach to addressing the HIV epidemic, but uptake is unequal across populations at elevated risk for HIV. Furthermore, the PI has found that rates of substance use are increasing among sexual minority YMSM. Research has largely failed to consider the role of interpersonal, community, and societal factors that thwart PrEP uptake and exacerbate substance use among AA/HL YMSM. A robust training plan is proposed that includes three core areas for skill development: (1) HIV- related intervention development; (2) qualitative methods to gain in-depth understanding of perspectives and experiences of minorities with substance use; and (3) content expertise in HIV prevention, problem substance use, and minority stress. The plan involves a mentorship team of six HIV and substance use prevention scholars, individualized trainings, coursework, and professional conferences. Career goals include a subsequent R01 application and the creation of a sexuality-focused niche in HIV and substance use prevention. Career development will take place at the University of Connecticut in collaboration with leading institutions and centers in New England. Based on our preliminary work, we propose three studies that explore the role of sexual identity and disclosure in PrEP and substance use experiences across the PrEP care continuum. We will address three specific aims. Specific Aim 1: Informed by a minority stress model, evaluate PrEP uptake and substance use among YMSM in a national cohort. We will collect new national data (N = 3,000 18 to 29-year-old AA/HL YMSM) to evaluate how diverse interpersonal, community, and societal factors affect PrEP uptake and substance use. Specific Aim 2: Define the PrEP care continuum for YMSM with and without substance use (from Aim 1). We will do so via four biyearly follow-up surveys (N = 300) over 24 months from participants in areas of high HIV incidence. Specific Aim 3: Perform semi-structured interviews among YMSM for future sexuality-informed PrEP/SU interventions (N = 30). How multiple barriers are related to substance use and PrEP uptake will be explored. Additionally, using the ADAPT-ITT model and based on previous findings, the we will identify the modifiable characteristics among current interventions that can be applied to prevention program...