The significant and harmful role that alcohol consumption plays on the HIV epidemic in the U.S. and worldwide has only recently begun to be recognized. Therefore there is urgent need to train new researchers in this field. Dr. Judy Hahn, Associate Professor in Residence, University of California, San Francisco, is a leading epidemiologist studying within-person alcohol consumption patterns and associated risk behaviors, and the effect of alcohol consumption on HIV outcomes by persons living with HIV in Uganda and among young adult injecting drug users (IDU) in San Francisco. A distinctive hallmark of her research is the characterization and use of a direct metabolite of alcohol, phosphatidylethanol, to supplement frequently unreliable self-report. Dr. Hahn proposes to use K24 dedicated time to mentor USCF as well as Ugandan investigators in patient oriented alcohol/HIV research. Her mentees will gain hands-on research experience, training in data analysis, manuscript preparation, and grant writing, as well as career mentoring. Mentee training will leverage the infrastructure and resources of Dr. Hahn's ongoing longitudinal cohort studies (R01 AA018631 and U01 AA020776) and her collaborations with multidisciplinary researchers in the areas of alcohol, substance use, and HIV domestically and worldwide. In order to increase her mentoring skills, she proposes to participate in the UCSF Mentor Development Program and to engage in individualized training from a mentoring coach. To extend Dr. Hahn's research to conduct interventions reduce the impact of alcohol on the HIV epidemic, she will obtain training in implementation science, a field that aims to maximize the impact of applying evidence-based interventions to new settings. She will examine existing public health infrastructure such as HIV prevention, testing and treatment programs as possible avenues for incorporating alcohol interventions such as screening and brief intervention (SBI). Lastly, Dr. Hahn proposes to conduct K24 supported alcohol research studies that will serve as training vehicles for mentees and expand her research. These studies, using biomarkers of alcohol consumption to supplement self-report, will be conducted using data from her ongoing NIH-funded cohort studies of persons with HIV in Uganda and young adult IDU in San Francisco to examine (1) factors associated with under-reported alcohol consumption and (2) factors associated with spontaneously reducing alcohol consumption. She will additionally conduct formative work to explore potential avenues of interventions relevant to these two diverse settings. In summary, this K24 will leverage Dr. Hahn's active research program with extensive infrastructure at UCSF to support a program of