PROJECT SUMMARY Homeless emerging adults (18-25 year olds) have alarmingly high rates of alcohol and other drug use (AOD), which is associated with a range of sexual risk behaviors such as unprotected sex, trading sex, and sex with multiple casual partners. Few risk reduction programs for this population have been developed and rigorously evaluated, particularly those that address both of these interrelated behaviors, use a collaborative and non-judgmental approach, and are feasible to deliver in settings where homeless young people seek services. Our team recently developed and pilot tested AWARE, a brief Motivational Interviewing (MI)-informed group risk reduction intervention for homeless 18-25 year olds that incorporates education, skills building, and personalized feedback. AWARE consists of four 45-minute sessions that focus on both AOD use and sexual risk behavior. Pilot results demonstrate the acceptability and feasibility of AWARE, as well as positive effects on AOD and sexual risk behavior outcomes over a 3 month period. The proposed R01 continues this line of research by conducting a larger-scale evaluation of AWARE. In collaboration with four agencies serving homeless youth in Southern California, we propose to randomize N=400 homeless 18-25 year olds to receive either the AWARE program or standard drop-in center care and evaluate substance use and sexual risk behavior at 3, 6, and 12 month follow-up. In addition, we will significantly extend our pilot work by evaluating whether AWARE, by motivating homeless emerging adults to make healthier choices, has positive secondary effects on health-related quality of life and social stability. Finally, we will examine the effects of group-level change talk (one hypothesized mechanism of action for group MI) on individual AOD and sexual risk behavior outcomes. Results from this innovative study have the potential to fill a significant gap in prevention services for homeless emerging adults by demonstrating that a brief intervention, feasible to deliver within settings where this population typically seeks services, can significantly reduce the interrelated problems of AOD use and sexual risk behavior.