Solid as a rock, flexible as water? Effectiveness of a school-based intervention addressing students' intrapersonal and interpersonal domains.

Students following a preparatory vocational education track seem most in need of an intervention stimulating their competencies and preventing the development of problems in the intrapersonal and interpersonal domain. The aim of the present study was to examine, first, whether Rock & Water, a social emotional learning intervention that uses active forms of learning, is effective in improving students' competencies and preventing problems in the intra- and interpersonal domain, and second, whether intervention effects were influenced by the extent to which multiple systems are involved in the intervention. We conducted a randomized controlled trial with a sample of 7th grade students (N = 1299, M = 12.38, 54% boys). Students reported on outcomes of the intra- and interpersonal domains using digital questionnaires. The data were analyzed with Latent Growth Curve models. Results showed that the intervention was most effective when only a core team of teachers was involved in the intervention. The intervention improved several proximal outcomes (i.e., self-control and emotional self-regulation) and distal outcomes in students' intrapersonal and interpersonal domains. The intervention effects were strongest, albeit moderate, in the first year of the intervention. These results show that interventions with an active form of learning and implemented by a core team might be promising interventions for prevocational students, although effort should be put in increasing its effectiveness.