Depression among urban adolescents in South Africa is a significant public health issue warranting comprehensive intervention strategies. A mixed-methods approach combining quantitative surveys with qualitative interviews to assess changes in depressive symptomatology and associated factors over a one-year period. Significant reductions (p < .05) were observed in depressive symptom scores, indicating the efficacy of the intervention programmes. The school-based mental health programmes demonstrated promising outcomes for reducing depression symptoms among urban adolescents in South Africa. Further implementation and expansion of these programmes are recommended to address ongoing mental health needs within this demographic. Treatment effect was estimated with $\text{logit}(p_i)=\beta_0+\beta^\top X_i$, and uncertainty reported using confidence-interval based inference.