Schools are the most logical places for early intervention, providing an environment in which adults can observe the behavior of children and adolescents in a continuous, systematic manner. The three major types of school-based early intervention programs are those based on school policies, staff training programs, and school-based service programs. The health care system provides the most likely site for the identification of and intervention with young substance abusers. The two primary categories of early intervention programs in the health care system are screening, assessment, and referral services; and brief interventions. Early intervention in the juvenile justice system, both pre- and post-adjudication, is based on the concern that the prosecution of young drug offenders may promote their later criminal careers. Two models of programs operating in community settings are evaluated here: the Strengthening Families Program and the Adolescent Transitions Program. 4 references