SUMMARY The majority of persons with HIV (PWH) in the US consume alcohol, despite that alcohol use is associated with lower levels of HIV care engagement and HIV viral suppression. Over the past decade, our research team has established the Florida Cohort to support research and training with a mission to maximize HIV viral suppression and improve health outcomes in PWH. Key features of the Florida Cohort include a focus on alcohol-related issues, academic and community-based partnerships across the state, targeted enrollment of diverse populations, and linkage to statewide HIV surveillance data. Meanwhile, several agencies in Florida are implementing new interventions to help achieve HIV viral suppression, including the PositiveLinks (PL) app. The overarching goals of the current grant proposal are to advance understanding of the mechanisms influencing adherence to contemporary HIV therapeutic regimens, and to incorporate alcohol-related interventions into emerging strategies to achieve and maintain HIV viral suppression across diverse populations. We propose to enroll and survey 1200 new Florida Cohort participants, with targeted enrollment for heavy drinkers and sexual/ethnic minorities. The survey data will allow us to identify multilevel factors contributing to ART adherence and viral suppression among alcohol-using PWH. From the overall cohort, 80 alcohol-using PWH will complete “enhanced monitoring (EM)” for one month. The EM group will wear a wrist alcohol biosensor, report alcohol and other risk factors (e.g., real-time anxiety, depression) and ART adherence through an ecological momentary assessment (EMA) app, and provide two dried blood spots (DBS) viral load tests. The EM data will help disentangle the temporal relationships between alcohol, other risk factors, and ART adherence in real-time. Survey and EM data together with input from the EM participants will be used to inform the development of several aspects of the biosensor-based intervention. Our interdisciplinary team will also meet regularly with a new Community/Provider Advisory Board (CAB), who will provide input related to the ongoing Florida Cohort (e.g., enrollment, survey design) and help develop a plan to integrate the alcohol biosensor-based intervention into the PL app. The specific aims include: 1) Systematically investigate multilevel factors based on the social-ecological model and WHO model that influence ART adherence and subsequently HIV viral suppression in alcohol-using vs. non-using PWH. 2) In 80 alcohol-using PWH, use alcohol biosensors and EMA data to identify alcohol consumption patterns and risk factors most strongly associated with ART non-adherence and poor HIV viral suppression. 3) Develop an intervention that incorporates an alcohol biosensor into an existing mHealth ART adherence intervention, with input from alcohol-using PWH and a Community/Provider Advisory Board. The rich information we collect in this project will establish a solid foundation fo...