Esther Mertens

| 45 Effectiveness of a Psychophysical Intervention Solid as a Rock, Flexible as Water? Effectiveness of a School-Based Intervention Addressing Students’ Intrapersonal and Interpersonal Domains Schools play an eminent role in fostering students’ development in the intrapersonal and interpersonal domain (Pellegrino & Hilton, 2012). The intrapersonal domain refers to the ability to manage one’s own feelings, emotions, and attitudes that pertain to the individual self, such as psychological wellbeing and internalizing behavior (Barber, 2005). The interpersonal domain refers to the ability to build and maintain positive relationships with others, to understand social situations, roles and norms, and to respond appropriately, such as interpersonal relations and aggression (Pellegrino & Hilton, 2012; Shek & Leung, 2016). Students can gain competencies in these domains by mastering relevant cognitive, affective, and social skills (e.g., identifying emotions, perspective taking) or can develop problems when mastery of (some of) these skills lacks or falls behind (Durlak, Weissberg, Dymnicki, & Taylor, 2011; Modecki, Zimmer- Gembeck, & Guerrà, 2017). Although the two domains influence each other, they are regarded as distinct domains. The intrapersonal domain reflects subjective personal functioning, predicting for instance academic functioning, whereas the interpersonal domain reflects social functioning, predicting for instance positive peer relations (Dufner, Gebauer, Sedikides, & Denissen, 2019; Park et al., 2017). Therefore, schools should intentionally cultivate their students’ competencies and prevent development of problems in both domains (Pellegrino & Hilton, 2012). Many schools implement universal interventions addressing students’ intra- and interpersonal domains. However, these interventions show only small effects for students in general (see for a meta-analysis Mertens, Deković, Leijten, Van Londen, & Reitz, 2020) and might show even smaller effects for certain groups of students. In the Dutch secondary education system, starting at age 12 (7 th Grade), there are three educational tracks: Preparatory vocational track (i.e., prevocational track), preparatory college track, and preparatory university track. More than half (54%) of the total secondary student population attends the prevocational track (Central Bureau for Statistics, 2020). These students in particular seem to be in need of school’s stimulation of competencies and prevention of problems in the intra- and interpersonal domains as they report lower levels of wellbeing, more behavioral problems, more problems with peers (Stevens & DeLooze, 2018), and have an increased risk for psychological problems (Schrijvers & Schuit, 2010) compared to students in the other two educational 3