For the most part, information concerning the effects of preventive interventions for youth at risk is more anecdotal than scientific. There have been few longitudinal studies with adequate control groups. Conceptual, methodological, and theoretical complexities limit our ability to assess program effectiveness adequately. As scientific knowledge in secondary prevention (selective, indicated prevention) is scarce, the Federal Office of Public Health in Switzerland established the national program, supra-f (Suchtpräventions-

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