PROJECT SUMMARY AND ABSTRACT Alcohol is the most prevalently used substance among gay and bisexual men (GBM). Additionally, alcohol is inextricably linked to GBM culture and often used as a precursor or enabler of sexual activity. Alcohol-involved sex often involves engaging in sexual behavior that places persons at higher risk for HIV seroconversion such as condomless anal sex. Pre-exposure prophylaxis (PrEP) is effective in preventing HIV-seroconversion, but recommended medication formulations are daily pills with moderately high levels of adherence to be most effective. Substance-using GBM have been shown to have lower levels of adherence compared to non-using GBM, but scant research has investigated the impact that alcohol consumption has on PrEP adherence. Therefore, the proposed study will collect pilot data to investigate the effects of alcohol use and misuse on PrEP adherence. In this mentored career development award (K01), Dr. Westmoreland will describe patterns of alcohol use and sexual behavior among PrEP-using GBM, identify the role that alcohol use plays in daily PrEP adherence using multiple methodologies to collect aggregate (e.g., 30 day) and detailed (e.g. ecological momentary assessment (EMA)) data, and contextualize PrEP non-adherence related to alcohol consumption. In Aim 1, Dr. Westmoreland will use baseline qualitative and quantitative data to describe patterns of alcohol use and sexual behavior. She will also use the narratives from qualitative interviews to add to the growing literature surrounding barriers to PrEP uptake and engagement in the PrEP care continuum. In Aim 2, Dr. Westmoreland will use multiple sources of data—i.e. quantitative surveys, timeline follow-back interviews (TLFB), diary entries collected twice-weekly for 10 weeks (i.e. EMA data), and dried blood spot (DBS) specimens for alcohol and PrEP adherence monitoring—to quantitatively identify the role that alcohol plays in daily PrEP adherence. By using multiple data collection techniques, she will also be able to pinpoint and validate estimates of alcohol use and PrEP adherence. In Aim 3, Dr. Westmoreland will use qualitative data from follow-up interviews to contextualize PrEP non-adherence related to alcohol consumption. Additionally, she will use these follow-up interviews to help characterize participants’ perceived changes in risk over the follow-up time period that could lead to deviations from daily PrEP use. Dr. Westmoreland will build on her prior training as a STI and HIV epidemiologist to expand her expertise into alcohol research and develop new analytical skills needed to conduct impactful sexual behavior research. These skills will include collecting and analyzing qualitative data; working with EMA, TLFB, and DBS data; implementation science, grant-writing, and scientific communication. Through methods coursework and workshops, alcohol-focused workshops and seminars, mentorship, and professional meetings, Dr. Westmoreland will gain the skil...