This Handbook explores the origins, development, and course of substance use as it emerges and unfolds in adolescence. Given the large causal network involved in adolescent substance use and abuse as well as its powerful impact, both at the time of use and in terms of the long term outcomes and complications of use, the domains covered by this volume range from infancy to adulthood, and from molecular genetics to social policy. The book is organized into eight sections, beginning with a review of the conceptual framework. It explains why a developmental framework is essential in understanding the adolescent period and goes on to discuss the epidemiology of substance use and abuse. It then examines the similarities and differences among the different drugs of abuse, namely: nicotine, alcohol, marijuana, prescription drugs, and other illicit drugs. The remaining sections deal with etiology and course in the context of adolescent development; the correlation between developmental tasks and adolescent substance abuse; clinical symptomatology and comorbidity; and the different assessment and intervention methods that have been developed to address the problem of adolescent alcohol and other drug abuse. These interventions include targeted prevention approaches, family-based treatments, twelve-step approaches, and inpatient and outpatient models. The book concludes with a chapter that analyzes the multi-level structure of public policy for the prevention of alcohol, tobacco, and drug problems among the youth.