Treatment of adolescent substance abuse poses difficult challenges to social work practitioners. Effective intervention requires awareness of assessment and treatment approaches and knowledge of individual, peer, and family factors that contribute to alcohol or drug use. Social work's emphasis on contextual factors in the etiology and maintenance of addictive disorders is an important contribution to substance abuse treatment. Practitioners are in an excellent position to implement interventions addressing multiple causes of substance abuse. This paper discusses the prevalence of alcohol and drug use among adolescents in the United States. Assessment issues are identified and promising approaches to treating adolescents with substance use problems are noted. Implications for social work practice and research are delineated.