Routine monitoring data are an underused but important source of insight into large-scale, real-world program implementation. Three years into implementing its mental health programme called MindSKILLZ, Grassroot Soccer, an adolescent health organization, initiated a multi-country analysis of its routine monitoring data to: 1) examine MindSKILLZ effects overall, by mental health construct, country, delivery method, and participant characteristics; and 2) gather feedback from experts and youth on the MindSKILLZ pre-post questionnaire to improve its design. Pre-post questionnaire data from 2,286 participants in Kenya, Zambia, and Zimbabwe were analyzed. Results demonstrate statistically significant improvements across countries. Program participants showed substantial gains in stigma reduction (+44.8%), help-seeking (+43.6%), and mental health knowledge (+34.2%). Clinically meaningful improvements in mental well-being were observed in Zimbabwe (+16 points), alongside positive change in Zambia (+6 points). Feedback from experts and youth highlighted challenges with the pre-post questionnaire (e.g., youth comprehension), prompting pre-post tool revisions. Findings demonstrate the value of routine monitoring data for identifying trends in program outcomes and guiding ongoing program improvement. Research studies are needed to establish causal impacts of programming.