This article use a meta-analysis research design to synthesize 33 randomized controlled trials focused on mindfulness-based interventions with 3,666 child and adolescent participants. The results indicated that mindfulness-based interventions led to significantly greater improvements in mindfulness and executive functions as compared to controlled conditions. Post-intervention benefits were noted for depression and anxiety/stress, as well as negative behaviors. These results support mindfulness as an effective intervention for cognition and mental health in children and adolescents.