This mixed methods study investigated the impact of a music therapy group on the capacities for emotion-related self-regulation in primary school learners situated in a context of community violence, as well as how the learners interpreted and experienced the process. Twelve participants were recruited. Seventeen weekly group music therapy sessions were conducted at the participants’ school, all of which were video recorded and transcribed. A concurrent parallel design was used, in which the quantitative and qualitative data were gathered and analysed independently and were integrated during the interpretation of results. The quantitative data included both learners’ and teachers’ pre- and post-test questionnaires, in-session activity ratings of sessions 1, 9, and 16 for each learner, and full session ratings of sessions 4, 7, 12, and 15 for each learner. The qualitative data were drawn from the last session with the learners, which took the form of a reflection discussion and art making process. An analysis of the qualitative data revealed six themes: music therapy helps in regulating “hot” feelings and behaviours; music therapy helps in regulating shy feelings and behaviours; emotional shifts attributed to music therapy; adaptive musical fidgeting; individual pacing within group flow; and joint group conversational flow. The quantitative data revealed significant positive changes in participants’ emotion-related self-regulation in the teachers’ pre- and post-test questionnaires for group one, the session ratings for group one, and the activity ratings for group two. Other quantitative measures also indicated positive changes, but these were not significant. The results of the qualitative and quantitative analyses were integrated. The participants, teachers, and music therapists involved in the study noted an improvement in participants’ self-regulatory capacities as the music therapy process progressed, however, the emotion-related over-regulation expressed through withdrawal and shyness did not seem to shift for many participants and future interventions could be improved by focussing more on over-regulated behavioural patterns.