Brief strategic family therapy (BSFT) is a manualized treatment designed to address aspects of family functioning associated with adolescent drug use and behavior problems (J. Szapocznik, U. Hervis, S. Schwartz, (2003). Brief strategic family therapy for adolescent drug abuse. (NIH Publication No. 03-4751). Bethesda, MD: National Institute on Drug Abuse). Within the National Institute on Drug Abuse's (NIDA's) Clinical Trials Network, BSFT is being compared to treatment as usual (TAU) in a multisite, prospective randomized clinical trial for drug using adolescents and their families in outpatient settings. The effectiveness of BSFT is being compared to TAU in reducing adolescent drug use, conduct problems, and sexually risky behaviors as well as in improving family functioning and adolescent prosocial behaviors. This paper describes the following aspects of the study: specific aims, research design and study organization, assessment of primary and secondary outcomes, study treatments, data analysis plan, and data monitoring and safety reporting.