Project Adhere has three primary aims that will be accomplished via periodic mobile surveys and in-depth qualitative interview: (1) to characterize patterns of PrEP use, discontinuation and adherence among young black men who have sex with men (YBMSM) in Atlanta, GA, (2) to explore psychosocial protective and risk factors associated with PrEP persistence, and (3) to identify psychosocial targets for mobile interventions to support PrEP adherence among YBMSM.