Art-based interventions, such as classroom drama workshops (CDWs), increasingly form part of a collection of mental health-promoting activities introduced in school settings. While research points to the potential benefits of CDWs for the mental well-being of refugee and migrant adolescents, the mechanisms to such improvement are less understood. In this article we respond to the need for qualitative evidence of how CDW interventions affect refugee and migrant adolescents’ experience. The study draws on eight focus group discussions (FGDs) with 41 adolescents, four semi-structured interviews with teachers and a school coordinator, and written documents from two drama therapists. Our thematic analysis revealed that the CDWs were found to foster trust and improve social relations in the classroom—key facets of bonding social capital. Several processes were described as being linked to these changes. Participants spoke about how the CDWs were facilitated in an emancipatory and safe manner, creating social spaces where the adolescents could have fun together, share, and bear witness to each other’s stories, as well as experiencing a sense of agency. In some cases, however, activities in the CDWs crossed the learners’ psychological boundaries, which led to withdrawal and a loss of trust. We conclude that whilst CDWs have the potential to facilitate bonding social capital amongst refugee and migrant adolescents and their teachers, this potential hinges on how the CDWs are facilitated.