This meta-analytic review examines the effectiveness of 77 published evaluations of parent training programs aimed at enhancing parenting skills and improving children's behavior and adjustment from ages 0 to 7. The study uses program content and delivery methods to predict effect sizes on parenting behaviors and children's externalizing behavior. Key findings include that components such as increasing positive parent-child interactions, teaching emotional communication, using time-outs, and practicing new skills during training sessions are associated with larger effects. Components like teaching problem-solving, promoting cognitive or social skills, and providing additional services are linked to smaller effects. The results have implications for selecting and enhancing existing parent training programs, suggesting that specific components can significantly impact program outcomes. The study also highlights the importance of examining individual strategies and processes of change within parent training programs to identify essential components for greater effectiveness.This meta-analytic review examines the effectiveness of 77 published evaluations of parent training programs aimed at enhancing parenting skills and improving children's behavior and adjustment from ages 0 to 7. The study uses program content and delivery methods to predict effect sizes on parenting behaviors and children's externalizing behavior. Key findings include that components such as increasing positive parent-child interactions, teaching emotional communication, using time-outs, and practicing new skills during training sessions are associated with larger effects. Components like teaching problem-solving, promoting cognitive or social skills, and providing additional services are linked to smaller effects. The results have implications for selecting and enhancing existing parent training programs, suggesting that specific components can significantly impact program outcomes. The study also highlights the importance of examining individual strategies and processes of change within parent training programs to identify essential components for greater effectiveness.