While undernutrition among children is very pervasive both in Sub- Saharan Africa and South Asia, child mortality is rather low in South Asia. In contrast to that Sub-Saharan African countries suffer by far the worst from high rates of child mortality. This different pattern of child mortality and undernutrition in both regions is well known, but approaches using aggregated macro data have not been able to explain it appropriately. In this paper we analyze the determinants of child mortality as well as child undernutrition based on DHS data sets for a sample of six developing countries in South Asia and Sub-Saharan Africa. We investigate the effects of individual, household and cluster socioeconomic characteristics using a multilevel model approach and examine their respective influences on both phenomena. We find that the determinants of child mortality and undernutrition differ significantly from each other. Access to health infrastructure is more important for child mortality, whereas the individual characteristics like wealth and educational and nutritional characteristics of mothers play a larger role for anthropometric shortfalls. Although very similar patterns in the determinants of each phenomenon are discernable, there are large differences in the magnitude of the coefficients. Besides regressions using a combined data set of all six countries show, that there are still significant differences between the two regions although taking account of a large set of covariates.