Esther Mertens

| 21 General Introduction adjustment” and “social safety” which I later refer to as the “intrapersonal domain” and the “interpersonal domain”, respectively. The results of the effectiveness of R&W, compared to CAU, are reported in Chapter 3 and the effectiveness of universal school- based intervention in general in Chapter 6. Concerning the second aim, Chapter 3 shows whether the intervention’s ecological width and intervention’s time span affected intervention effects. The findings to what extent students’ personality affected intervention effects are presented in Chapter 4. With respect to the third aim, Chapter 5 reports whether classmates’ modeling and reinforcement mediated the effect of R&W on the peer context in the classroom. Chapter 6 presents which components were related to stronger and weaker intervention effects of universal school-based interventions in general. Last, Chapter 7 discusses the main findings and put the findings of R&W in the general framework of universal school-based interventions provided by the meta-analysis. 1