Children who engage in aggressive behaviors are at heightened risk of being involved in the justice system, committing serious offenses, and becoming chronic offenders. The Stop Now And Plan (SNAP) program was designed as an early intervention to address several mechanisms underlying the development of conduct problems, including emotion regulation, prosocial behaviors, and parent-child relationships. The purpose of this study was to systematically review and synthesize current research on the SNAP program and conduct a meta-analysis. Following PRISMA guidelines, PubMed and PyscINFO were searched, and the developers of SNAP were contacted to ensure no articles were missed. Twenty-two peer-reviewed articles were ultimately included following a two-stage screening process. The meta-analysis revealed a moderate effect size change (SMD = -0.54, 95% CI [-0.42, -0.65], p < 0.001) in externalizing problems from pre- to post-SNAP Group. The narrative review found evidence for decreases in symptoms (e.g., conduct problems, aggression, delinquency, internalizing problems) across SNAP programming. There was also preliminary evidence for changes in proposed mechanisms across the groups (e.g., emotion regulation, parent behaviors, child-parent relationship). Two randomized controlled trials (RCT) supported the efficacy of the SNAP Boys Group over another active treatment. One waitlist control found similar results for the SNAP Girls Group. There is growing evidence for SNAP, attributable to the effective clinical research partnerships established by the developers. More rigorous methods and RCTs will help solidify SNAP as a top evidence-based intervention.