Significance. In the US, young, black men who have sex with men (YBMSM) are disparately impacted by HIV. For many YBMSM, heavy drinking or problems related to alcohol use adversely impacts their HIV care and treatment. Thus, interventions to improve HIV treatment outcomes and reduce heavy drinking in HIV-infected YBMSM in HIV treatment are urgently needed. Career Development Plan. Dr. Knox's training will include developing critical skills in intervention research and implementation science, and substantive training in HIV care and treatment. This will be achieved through a plan that includes seminars, workshops, coursework, conferences, and tailored mentoring. These activities will help Dr. Knox become an independent investigator with a research program focused on understanding and addressing HIV and alcohol use in vulnerable populations. Research Plan. In Aim 1, Dr. Knox's proposed research involves conducting formative work to inform the development of an intervention that addresses HIV treatment and alcohol use in heavy-drinking, HIV- infected, YBMSM. The intervention will borrow components from two distinct and potentially complementary, evidence-based clinic-based interventions that are brief and theory-driven. The first improves HIV treatment outcomes in HIV-infected YBMSM by involving a member of their social network to support them in HIV care. The second intervention addresses alcohol use by using smartphone technology to engage participants daily in self-monitoring relative to drinking reduction goals formed during a brief, motivational component of the baseline intervention session. In Aim 2, the information from this formative work will be synthesized with the help of consultant workgroups made up of YBMSM and implementation partners. The product of Aims 1 and 2 will be an innovative intervention that leverages both social network support and technology to improve HIV treatment outcomes and reduce alcohol use in heavy-drinking, HIV-infected YBMSM. It will be administered as a single- session baseline intervention with brief follow-up check-ins. In Aim 3, the new intervention will be pilot tested to assess its potential efficacy, acceptability, feasibility and implementation against a randomly assigned control condition among 60 heavy-drinking, HIV-infected YBMSM in an HIV clinic in New York City (NYC). As an epicenter of the HIV epidemic, interventions for young, black MSM in HIV treatment are urgently needed in NYC. The results of this pilot test will inform the development of an R01 proposal for a fully powered randomized controlled trial to evaluate the efficacy and implementation of the developed intervention. Mentorship. A team of expert investigators in alcohol and drug use, HIV, racial and sexual minorities, intervention development, implementation science and mixed methods will support this research. Public Health Impact. The project aims to reduce disparities in HIV treatment outcomes and, in turn, incidence of new HIV infec...