Esther Mertens

| 133 Components of School-Based Interventions Discussion It is important to understand the intervention components that contribute to intervention effectiveness, or ineffectiveness, in order to guide intervention selection and implementation. Schools strive to improve their students’ wellbeing, but their time and resources to invest in interventions are limited. This meta-analysis aimed to identify the intervention components that contribute to the effectiveness of universal secondary school-based interventions aiming to stimulate students intra- and interpersonal domains. In line with previous meta-analyses examining universal school-based interventions, we found small positive effects on students’ intra- and interpersonal domains (e.g., Dray et al., 2017; Durlak et al., 2011; Jiménez-Barbero et al., 2016). Overall, none of the discrete components were consistently related to stronger or weaker effects on both students’ intra- and interpersonal domains across the subdomains. In other words, components that were related to stronger or weaker intervention effects typically were so for more specific domains only. In terms of the type of components that matters most, content components seemed more relevant for stimulating the intrapersonal domain (e.g., self-esteem), and structural components seemed more relevant for stimulating the interpersonal domain (e.g., bullying). Importantly, components related to stronger intervention effects were not necessarily frequently implemented in interventions (e.g., in 10% - 19% of the interventions). Similarly, components related to weaker intervention effects were generally implemented frequently (e.g., in 40% - 53% of the interventions). Content components teaching students self-awareness (i.e., insight building) and problem solving were related to stronger effects, whereas components teaching emotion regulation and assertiveness were related to weaker effects. These findings are in line with previous research that indicated teaching self-awareness and problem solving as potential effective components (e.g., Boustani et al., 2015). Teaching emotion regulation and assertiveness might be more relevant in different contexts than the secondary school context in which the interventions were implemented. For instance, emotion regulationmight bemore relevant when implemented in psychotherapy (e.g., Weisz et al., 2012) and teaching assertiveness might be more relevant for students at elementary schools (e.g., Onrust et al., 2016). In other words, content components might be differentially related to intervention effects in different contexts. In general, instructional components that reflect an active learning approach were related to stronger intervention effects (e.g., relaxation, practice). This does not mean that interventions should only use active learning approaches and exclude more passive learning approaches. Interventions that used discussion as method delivery, an active learning component, were related to weaker intervention effects on aggression, whereas interventions using a didactic information delivery as method, a passive learning approach, were related to stronger intervention effects. These findings are in line with the meta-analysis of De Mooij, Fekkes, Scholte, and Overbeek (2020) that 6