International child health programmes in low-income countries are justified in term of their impact on child survival. However, the effect estimates are usually calculated from performance indicators and assumptions about efficacy based on small-scale target-specific studies. There is little follow-up of how the programmes are implemented in real life.This approach is clearly not sufficient. Recent studies have consistently shown that vaccines and micronutrients have non-specific effects, i.e. effects which are not explained by prevention of the targeted infections or deficiencies. These effects are often sex-differential. Furthermore, interventions may interact. Hence, the overall impact of child health programs can not be extrapolated from small-scale target-specific studies. There is a need to assess the real life impact and cost-effectiveness of child health intervention programmes in the context where they are being used.We propose to use health and demographic surveillance system (HDSS) sites in Africa to register information routinely on all interventions in childhood, such as all vaccinations, micronutrient supplementation, and de-worming, given at health centres or in campaigns. Using this information we will measure the overall health impact of the child health programs.The HDSS platform can also be used for testing modifications of the current health programmes. We will test a recent finding from a randomised trial in Guinea-Bissau: providing early measles vaccine at 4.5 and 9 months of age compared with the recommended measles vaccine at age 9 months reduced overall mortality from 4.5 to 36 months of age by astonishing 49%.The HDSS sites already collect data on mortality, and mortality would be the main outcome, but we also aim to identify other relevant comparable outcome parameters which correlate with mortality and which can be used to assess the overall impact of existing and new interventions.