Abstract
The conceptual importance of preventive interventions rests upon their ability to produce effects across time, settings, and behaviors. The present studies investigate whether a school-based preventive intervention, for high-risk adolescents, which has shown short-term effects of reducing predisposing factors, will show long-term effects of reducing school and community delinquency problems and substance abuse. School records and interviews 1 year after the program and arrest records at 5 years all suggest that the intervention reduced delinquency problems. The evidence was less clear for substance abuse. It was concluded that a better method for detecting substance abuse is needed before that question can be answered. The paper also discusses processes that may have mediated the delinquency results and implications for future prevention research.