In order to be better able to initiate preventive interventions aginst the use of drugs among children and adolescents, it is important to get an overview of the effectiveness of such initiatives. We included ten systematic reviews of high methodological quality. Based on our results and our assessment of the quality of the documentation for long-term effects of the preventive interventions in the ten included systematic reviews, we draw the following conclusions: Comprehensive school-based interventions to prevent the use of alcohol and marijuana are effective in preventing the use of both alcohol and marijuana among 10-15 year olds. School-based interventions, which emphasize skills, to prevent the use of illegal drugs may be effective in preventing the use of hard drugs among children and adolescents. The following interventions to prevent smoking may possibly be effective: i) mass-media campaigns, ii) school-based interventions that emphasize social skills, iii) parenting programs for children aged 5-11 years. The following prevention interventions may possibly be effective: i) school-based interventions against illegal drugs which emphasize knowledge to prevent use of marijuana, ii) parenting programs to prevent the use of tobacco, alcohol, and other drugs among adolescents aged 11-14 years, iii) family-based interventions to prevent alcohol abuse among children and adolescents, iv) multi-component interventions to prevent alcohol abuse among children and adolescents. School-based interventions, which emphasize knowledge, to prevent the use of alcohol and marijuana are possibly not effective in preventing alcohol abuse among adolescents aged 10-15 years. Family-based interventions to prevent smoking among children and adolescents are possibly not effective in keeping children and adolescents smoke-free.