Esther Mertens

| 115 Components of School-Based Interventions and problem solving, and components that included cognitive restructuring, adjusting social norms (e.g., peer education), and parental involvement predicted stronger substance use reductions. Hennessy and Tanner-Smith (2015), focusing on alcohol use, found that in secondary school components that included an individual and motivational enhancement approach were more effective in reducing alcohol use. In the present meta-analysis, we examined which components are related to more (or less) effective school-based interventions addressing students’ intra- and interpersonal domains. We focused on a broad range of outcomes to unravel which components are important for improving students’ overall development in the two general domains, and which components are important for improving specific competencies and problems in the two domains. We studied relations between components and intervention effects across different populations and circumstances. Although the effectiveness of components can be dependent on characteristics of participants and circumstance, our meta-analysis provides an initial overview of potentially relevant components in general. We analyzed all three types of components (i.e., content, instructional, and structural) and tested whether interventions with a specific component showed larger (or smaller) effect sizes than interventions without that component, usingmultilevel meta-regression. This enabled us to identify not only which components were associated with stronger effects, suggesting potential effective components, but also components associated with weaker effects, suggesting potential ineffective components. Knowing what does not work is equally important as knowing what does work (e.g., Poulin, Dishion, & Burraston, 2001; Werch & Owen, 2002). Concerning content components, based on the results of Onrust and colleagues (2016) and Boustani and colleagues (2015), we hypothesized that basic life skills and self-awareness would be related to stronger intervention effects on students’ intra- and interpersonal domains. Basic life skills refers to abilities for adaptive and positive behavior to deal with demands and challenges of everyday life (World Health Organization, 1997). Several reviews suggest the importance of basic life skills, such as problem solving, assertiveness, and social skills, for a range of outcomes of effective school-based interventions (e.g., intra- and interpersonal domains, Boustani et al., 2015; drug use, Cuijpers, 2002). Self-awareness indicates a realistic and accurate assessment of one’s strengths and norms, and is related to improvements on the interpersonal domain (e.g., Shek & Leung, 2016). Raising self-awareness, such as insight building and self-efficacy, is often used in effective interventions targeting the intrapersonal and interpersonal domains (Boustani et al., 2015). For instructional components, we hypothesized that components using a more active learning approach, in which students interact with each other and perform tasks (e.g., practicing through role-play), would be related to stronger intervention effects. Active learning approaches have consistently been related to stronger effects. For instance, Kaminski and colleagues (2008) found in their meta-analysis that parenting interventions in which parents practiced the learned skills were more effective than 6