The European Union Dataprev project reviewed mental health interventions in schools, focusing on parenting, schools, the workplace, and older people. The schools workpackage conducted a systematic review of reviews, identifying evidence-based interventions and programs and extracting general principles. The review found 52 systematic reviews and meta-analyses of mental health interventions in schools, which had beneficial effects on children, families, and communities across various mental health, social, emotional, and educational outcomes. Most interventions had small to moderate effect sizes, but their real-world impacts were large. The effectiveness of interventions varied, and their success was influenced by several factors, including teaching skills, focusing on positive mental health, balancing universal and targeted approaches, early intervention, and long-term implementation. Whole-school interventions were particularly effective when implemented with clarity, intensity, and fidelity. The review also discussed the implications for policy and practice, suggesting a rebalancing of priorities and emphases in school mental health promotion.The European Union Dataprev project reviewed mental health interventions in schools, focusing on parenting, schools, the workplace, and older people. The schools workpackage conducted a systematic review of reviews, identifying evidence-based interventions and programs and extracting general principles. The review found 52 systematic reviews and meta-analyses of mental health interventions in schools, which had beneficial effects on children, families, and communities across various mental health, social, emotional, and educational outcomes. Most interventions had small to moderate effect sizes, but their real-world impacts were large. The effectiveness of interventions varied, and their success was influenced by several factors, including teaching skills, focusing on positive mental health, balancing universal and targeted approaches, early intervention, and long-term implementation. Whole-school interventions were particularly effective when implemented with clarity, intensity, and fidelity. The review also discussed the implications for policy and practice, suggesting a rebalancing of priorities and emphases in school mental health promotion.