There is evidence that appropriately structured sport programmes can help young people to build positive life skills while also improving their physical fitness and psychological well-being. Disadvantaged and marginalised young people have relatively low rates of participation in sport, and designing programmes that attract and retain them presents a major challenge. Some success has been reported for programmes involving boxing, but such programmes entail a high potential for injury. The present study assessed the effects of a modified, low-risk form of boxing, known as Box'Tagon disadvantaged 11-12-year-olds. Volunteer Grade 7 students (N?=?51) participated in an eight-week programmes of two to three sessions per week. Using a matched-pair design to control for effects of gender and risk of social disengagement (at-risk/not-at-risk), participants were assigned to either the Box'Tagntervention or a control condition, in the form of a largely non-physical social skills programmes called Rock and Water. To assess aspects of psychological well-being, the Brunel Mood Scale (BRUMS) and the Strengths and Difficulties Questionnaire (SDQ) were administered at baseline (T1), at 4 weeks (T2), at 8 weeks (T3), and a follow-up at 12 weeks (T4). Participants completed a shuttle run and other fitness tests at T1 and T3. Qualitative feedback from participants (n?=?36) was gathered via open-ended questions at T3. No significant between-group differences were found for BRUMS or SDQ scores, although both the intervention and control groups reported significant reductions in total difficulties scores from T1 to T2 and the not-at-risk members of the Box'Tagroup reported the most positive trends for total mood disturbance from T1 to T2. The Box'Tagroup showed significant improvement in shuttle run performance from T1 to T3, whereas the control group showed no improvement. Programme perceptions were more positive for Box'Tagarticipants than for the control group, and behavioural benefits were found for both programmes. Overall, the Box'Tagrogramme appealed to children of both sexes, engaged children at risk of social disengagement, had positive effects on aerobic fitness, and yielded behavioural benefits for some participants.