This paper presents a critical review of selected literature about peer education initiatives with young people principally in the area of sexual health. Reported work in this area was found to be diverse in terms of aims, objectives, methods, findings and levels of evaluation. The paper highlights the promise of the method but draws attention to its potential problems. Examples of peer health education are reviewed and the issues surrounding them discussed. These include: theoretical background, rationales, cultural constraints, ethical and operational issues, and the challenges for monitoring and evaluation. The paper concludes by suggesting that practitioners and evaluators must reflect on the difficulties inherent in artificially reconstructing a social process.