Multicomponent positive psychology interventions are increasing in the general population but the study of its effectiveness in adolescents is still scarce, especially in the school context. Previous meta-analyses have reported that multicomponent positive psychology interventions increase well-being and reduce distress outcomes. However, the results on these outcomes limit their samples to adult populations. The aim of the current systematic review and meta-analysis is to evaluate and compare the immediate but also long-lasting effects of school-based multicomponent positive psychology interventions aimed at increasing well-being indicators of mental health (i.e., subjective and psychological well-being) and reducing the most common psychological distress indicators (i.e., depression, anxiety, and stress) in adolescents. A total of 9 randomized and non-randomized controlled trials from the searched literature met inclusion criteria for the meta-analysis. The results showed small effects for subjective well-being (g = 0.24), psychological well-being (g = 0.25), and depression symptoms (g = 0.28). Removing low-quality studies led to a slight decrease in the effect sizes for subjective well-being and a considerable increase for psychological well-being and depression symptoms. The relevant moderation analyses had an effect on subjective well-being and depression symptoms. The present systematic review and meta-analysis found evidence for the efficacy of school-based multicomponent positive psychology interventions in improving mental health in the short and long-term. Small effects for subjective well-being, psychological well-being, and depression symptoms were identified. Effects for psychological well-being and depression symptoms remained significant over time. In light of our results, education policy-makers and practitioners are encouraged to include positive practices within the schools' curriculum as effective and easily implemented tools that help to enhance adolescents' mental health. Further research is needed in order to strengthen the findings about school-based multicomponent positive psychology interventions in adolescents.
Keywords: Intervention; Meta-analysis; Multicomponent; Positive psychology; School; Well-being.