The prevention of youth problem behaviors is increasingly guided by science. Sound epidemiological research is coming to guide preventive efforts. Valid methods of monitoring the incidence and prevalence of youth problems increasingly shape preventive practice. The identification of empirically supported prevention interventions is becoming more sophisticated, and numerous scientific organizations have begun to engage in dissemination activities. These trends will be accelerated by increased media advocacy for the use of scientific methods and findings, the development of a registry of preventive trials, achievement of consensus about the standards for identifying disseminable interventions, and increased research on the factors that influence the effective implementation of science-based practices.