Esther Mertens

| 15 General Introduction Due to the psychophysical approach, R&W seems especially promising for prevocational students as this approach seems to fit in well with their learning processes. The recommended learning environment of this group of students is preferably characterized by a practical orientation in which students can practice the learned skills. When teaching prevocational students, short moments of instruction or reflection should be alternated with practical exercises. It is preferred to use activating methods and stepwise, structured tasks to help students regulate their learning processes. This teaching context is suggested to enable students to understand, use, and apply the learned knowledge more effectively (De Bruijn et al., 2005; Koopman, Den Brok, Bijaard, & Teune, 2011). Hence, the psychophysical approach of R&W seems a fitting intervention approach to target prevocational students as it uses a combination of shortly explaining or reflecting on the intervention techniques (i.e., a psychological approach) and physically practicing the intervention techniques in a relevant social context (i.e., a physical approach). Although R&W is broadly implemented in multiple countries (e.g., the Netherlands, Australia, China, Peru), little is known about its effectiveness. In the Netherlands 18,000 professionals have attended the basic training to become a certified R&W trainer and 65 schools have the R&W certificate (i.e., all students receive at least 10 R&W lessons each year and the entire school staff is trained in R&W). Results of previous research indicate that R&W is a promising intervention establishing improvements in both the intrapersonal (e.g., resilience, identity formation, coping styles; Ykema, Hartman, & Imms, 2006) and the interpersonal (e.g., coercive strategies; De Graaf, De Haas, Zaagsma, & Wijsen, 2016) domain. However, these studies were limited in samples (e.g., small sample size, only boys) and measurements (e.g., narrowly defined outcomes, self-reports, only a pre- and post-measurement). Therefore, I examined the effectiveness of R&W with an RCT design in a relatively large sample, including both boys and girls, measured a broad range of outcomes belonging to either the intrapersonal domain or the interpersonal domain, used students’ self-reports as well as parental reports and observations, and conducted measurements before, during, and after the intervention. Aim 1: Effectiveness of Universal School-Based Interventions In the current dissertation, the effectiveness of universal school-based interventions aiming to stimulate competencies and to prevent problems in the intra- and interpersonal domain was studied for R&W in specific and for universal school-based interventions in general. The effectiveness of R&Wwas examined with an RCT design, which is considered the “golden standard”, providing the most rigorous assessment of intervention effects as possible (Bonell, Fletcher, Morton, Lorenc, & Moore, 2012). Furthermore, the intervention was examined under real-world conditions rather than under optimal conditions highly controlled by researchers. For instance, R&W was 1