Extended the findings from previous meta-analytic work by comparing the effectiveness of behavioral parent-training (BPT) and cognitive-behavioral therapy (CBT) for youth with antisocial behavior problems. Youth demographic variables were also examined as potential moderators of the effectiveness of these 2 types of interventions. Thirty BPT studies and 41 CBT studies met inclusion criteria for this meta-analysis. The weighted mean effect size (ES) for all interventions was 0.40. Youth age was found to moderate the outcome of the 2 interventions, with BPT having a stronger effect for preschool and school-aged youth and CBT having a stronger effect for adolescents. The results also indicate that there may be systematic differences in the outcomes associated with BPT and CBT when the setting of the intervention is considered, suggesting the need to carefully consider the effect of setting in future research. This study also highlights the need for outcome research dealing with more diverse populations and the better classification of research participants on different developmental trajectories of antisocial behavior.