The study was a multi-wave panel study of the development of drug use and delinquent behavior among adolescents and young adults first interviewed when they were in seventh and eighth grades. The research purposely oversampled youth at high risk for serious delinquency and drug use. Information came from interviews of youths and their main adult caregivers as well as from school, police, court, and social service agency records. The research used two delinquency scales and measures of parental attachment and association with delinquent peers. Results revealed that family and peer variables did not relate to delinquent behavior in fundamentally different ways for early-onset juvenile offenders as compared with later-onset offenders. Findings also produced no support for developmental theories that suggest that early-onset and later-onset offenders require two distinct pathways or explanations for their delinquent behavior. Instead, more similarities than differences existed in the relative predictive power of family and peer variables for the two groups. Tables and 32 references