Little is known about the effectiveness of prevention and early intervention programs for young people and adolescents once they leave or dropout from school. The effectiveness of 18 anxiety and 26 depression studies addressing prevention in community programs were identified using systematic review methodology. Anxiety and depression symptoms were reduced in ~60% of the programs. Cognitive behavioral therapy programs were more common than other interventions and were consistently found to lower symptoms or prevent depression or anxiety. Automated or computerized interventions showed promise, with 60% of anxiety programs and 83% of depression programs yielding successful outcomes on at least one measure. Further research is needed to determine the active components of successful programs, to explore cost-effectiveness and scalability factors, to investigate individual predictors of successful outcome, and to design best practice prevention programs.