Cape Town, South Africa, faces a significant challenge in reproductive health education among adolescents, leading to misconceptions and poor practices. A mixed-methods approach was employed, including pre- and post-programme assessments through surveys (n=500) alongside qualitative interviews (n=30). Data were analysed using descriptive statistics for quantitative measures and thematic analysis for qualitative data. Pre-to-post knowledge gains in reproductive health concepts reached a mean increase of 42% among participants, with significant differences observed across gender and grade levels. School-based sex education programmes significantly improved knowledge and fostered positive practice changes in adolescent reproductive health behaviors. Continued implementation and refinement of these programmes are recommended to sustain and expand their impact.