Parent training is consistently highlighted as one of the most effective means of preventing delinquency and treating young children with conduct problems, and it has proven to be one of the most cost-effective interventions for doing so. There is, however, far less evidence supporting the efficacy of parent-training programs with adolescents and juvenile offenders. Nonetheless, it still seems to be one of the more promising methods for treating the behavior problems of adolescent delinquents, especially when used in conjunction with other carefully selected program components. We begin with an overview of parent training, highlighting the key components of successful programs. Research on the efficacy of parent training in the treatment of behavior problems among children and adolescents is discussed, particularly the differential impact of parental-training programs with specific groups of youths and families. We then discuss the ways in which parent training has been combined with other interventions in the treatment of delinquency. We conclude with a discussion of the problems encountered in implementing parent training, including recommendations for meeting the unique challenges of effective program implementation.