On average, 2,500 young people (15-24 years) get -infected with HIV every day; 80% of which live in sub-Saharan Africa. Since no cure or vaccine is available, reducing sexual risk behaviour in this group is crucial in tackling the epidemic. The general objective of this doctoral study was to improve the effectiveness of HIV prevention interventions for young people in sub-Saharan Africa. First, we assessed the overall effectiveness of such interventions (systematic literature review, meta-analysis). Secondly, we evaluated a school-based peer-led HIV prevention interventions in Rwanda (longitudinal, non-randomized controlled trial), to get insight into how interventions are developed, implemented and evaluated. While the first two objectives...