<qa>  What is the primary care setting a place for prevention interventions?The primary care setting represents an underutilized venue for prevention interventions addressing drug useabuse among youth. The purpose of the study is to: 1 develop and refine promising, empirically-derived, BMI preventionintervention modules delivered by a clinician or a computer to target marijuana use, and 2 test the effectiveness of BMI in preventing initiationescalation of marijuana use among youth in community health clinics. This randomized controlled trial screened adolescents in primary care clinics in Flint, MI. A random sample of those who screened negative for past year marijuana use were selected to participate in the study and all subjects who screened positive for past year use were enrolled in the study. These subjects were stratified by gender, age, and past year marijuana use and randomized to one of three conditions: 1 computer-delivered brief motivational approach BMI-C; 2 therapist-delivered brief motivational approach BMI-T; or 3 a NIDA drug education booklet. Primary outcomes are evaluated at 3-, 6- and 12-months and include marijuana, alcohol, tobacco and other drug use. Key moderators of effectiveness will be examined, including behavioral intentions, self-efficacy, stage of change, school involvement, susceptibility to peer pressure, and potential health consequences e.g., STDHIV risk behaviors. This project will provide the critical first step toward the implementation of tailored marijuana prevention and intervention in primary care clinics. 