Background: This research examined the impact of a programme integrating therapeutic music and group discussions (Holyoake's DRUMBEAT programme) on disadvantaged adolescents’ mental wellbeing, psychological distress, post-traumatic stress symptoms and antisocial behaviour. Method: Students displaying antisocial behaviours in grades eight to ten at three socio-economically disadvantaged secondary schools in Perth, Western Australia were invited to participate in a 10-week DRUMBEAT programme (incorporating drumming with djembes, therapeutic discussions and a final performance). Eight DRUMBEAT programmes were held in 2014. Pre- and post-intervention questionnaires measured mental wellbeing (Warwick–Edinburgh Mental Wellbeing Scale), psychological distress (Kessler-5), post-traumatic stress symptoms (Abbreviated Post-Traumatic Stress Disorder Checklist- Civilian Version) and antisocial behaviours (Adapted Self-Reported Delinquency Scale). Results: Of the 62 students completing DRUMBEAT, 41 completed pre- and post-questionnaires. Post-programme boys scored an average 7.6% higher mental wellbeing (WEMWBS) (p = .05), 19.3% lower post-traumatic stress symptoms (A PCL-C) (p = .05) and 23.9% lower antisocial behaviour (ARSDC) (p = .02). These changes were not evident for girls. No significant differences were detected for differences in psychological distress for either gender. Conclusion: This research highlights the potential of the DRUMBEAT programme as an effective, targeted strategy to reduce post-traumatic stress symptoms and antisocial behaviour and increase mental wellbeing in socio-economically disadvantaged adolescent boys.