Discusses the development of empirical guidelines in the design and evaluation of interventions for at-risk adolescents and adolescents already involved with drug use. Data is taken from the literature, from a cross-sectional study of 210 4th-, 7th-, and 10th-grade boys and their families, and from a longitudinal study of 200 boys and their families, initially assessed at age 9-10 yrs. Data indicate that (1) an effective family intervention should target parent monitoring, peer associates, parents’ drug use, and social skills and antisocial behavior; (2) at-risk youngsters can be identified earlier than adolescence; and (3) parent and peer training interventions are viable methods of preventing premature drug use.