Mental, emotional, and behavioral health disorders affect a large proportion of adolescents and young adults worldwide, and their prevention is a public health priority. Much research has identified the risk and protective factors that precede and influence the development of such disorders. In addition, many interventions have been developed to reduce risk factors and increase protective factors, and controlled trials or rigorous evaluations of many of these programs have indicated that they prevent the development of mental, emotional, and behavioral disorders. Despite this growing evidence of effectiveness, these programs are currently not being used at a sufficient scale to reduce rates of disorders worldwide. Additional effort and resources are needed to increase the number and use of effective prevention programs on a global scale.