Purpose: We undertook a systematic review and meta-analysis of intervention research studies focused on strengthening the social information-processing (SIP) skills of children. Methods: A systematic search and review process was employed to identify, screen, and summarize research on SIP-guided interventions. Results: The search recovered 183,184 citations published from 1997 to 2022. After screening, 42 articles were retained for a full-text review. Findings from the 15 studies using more rigorous designs [i.e., 8 individual-level randomized control trials (RCTs), 5 cluster-level RCTs, and 2 quasi-experimental studies with statistical controls for selectivity] suggest that SIP-focused interventions produced statistically significant treatment effects on cognitive skills, with mean effect sizes of 0.35 on encoding, 0.13 on hostile attribution bias, 0.13 on goal formulation, 0.16 on response decision, and—more behaviorally—0.37 on aggressive and disruptive comportment. Conclusions: SIP-focused interventions are effective. If widely implemented, they hold the potential to reduce aggressive behavior in childhood.