This component analysis used meta-analytic techniques to synthesize the results of 77 published evaluations of parent training programs (i.e., programs that included the active acquisition of parenting skills) to enhance behavior and adjustment in children aged 0–7. Characteristics of program content and delivery method were used to predict effect sizes on measures of parenting behaviors and children’s externalizing behavior. After controlling for differences attributable to research design, program components consistently associated with larger effects included increasing positive parent–child interactions and emotional communication skills, teaching parents to use time out and the importance of parenting consistency, and requiring parents to practice new skills with their children during parent training sessions. Program components consistently associated with smaller effects included teaching parents problem solving; teaching parents to promote children’s cognitive, academic, or social skills; and providing other, additional services. The results have implications for selection and strengthening of existing parent training programs.