ABSTRACT Sexual and gender minority individuals are more likely to report hazardous drinking and have alcohol use disorders (AUDs) compared to cisgender and heterosexual people. Emerging adult (aged 18-34) sexual and gender minorities are at especially high risk for AUDs compared to older adults, with up to 44% meeting AUD criteria. These trends are concerning, as studies have found that alcohol use increases HIV risk behaviors, and HIV disproportionately affects emerging adult sexual minority male and transgender (SMMT) individuals. Thus, it is essential to test interventions for reducing alcohol use among SMMT individuals as a means of preventing HIV among this vulnerable population. One potential evidence-based method of reducing alcohol use is motivational interviewing, which incorporates a goal-oriented approach for changing behavior and has been shown to be effective among various populations in prior literature and the investigators’ pilot research. However, there are opportunities to use technology to extend the impact of this approach by delivering messaging to prevent risk behaviors in real time (i.e., outside of intervention sessions). The proposed study will conduct a 3-arm randomized controlled trial that assesses the efficacy of two interventions as compared to a control: 1) An 8-week motivational interviewing intervention (TRAC) delivered remotely via cell phones and 2) TRAC combined with an ecological momentary intervention designed to deliver messages reinforcing drinking reduction strategies discussed during TRAC sessions when individuals visit risky locations (GeoTRAC). All participants will also complete monitoring of alcohol use and sexual behavior by completing daily surveys and twice-daily mobile breathalyzer readings. GeoTRAC will use an existing app developed in the investigators’ ongoing research that uses GPS tracking to determine when individuals visit “risky” locations. Participants will receive messages upon arrival at these locations reminding them of strategies to address triggers for drinking, and will also complete mobile surveys and breathalyzer readings when they leave these locations to determine what alcohol and/or risk behaviors they engaged in. If they reported drinking, they will receive harm reduction messaging to encourage them to avoid subsequent risk behavior (e.g., unprotected sex). Breathalyzer results and daily self-reports will be used to assess the primary and secondary outcomes of drinking days, drinks/drinking day, binge drinking episodes, and HIV risk behaviors, and additional assessments at baseline, 8 weeks, 6 months, and 12 months will evaluate exploratory long-term outcomes. Participants will be recruited from Kentucky and Connecticut through community-based recruitment and health clinics that serve SMMT individuals. Overall, there is a strong need to determine optimal methods of reducing alcohol use among emerging adult SMMT individuals given its relationship to increased HIV risk behavior...