Given its geographical, socio-economic, ethnic and cultural diversity, Cameroon offers an excellent setting for investigating the contribution of geographical and socioeconomic factors to mortality differences in infancy and childhood. Such research is crucial for designing appropriate health policies at the national and regional levels. Using data from a nationally representative sample of more than 12,000 births, this study assesses infant and child mortality differences in Cameroon by residence area, mother's education, ethnicity, marital status and union type, religion and the interplay of those factors on differentials mortality. The most vulnerable groups of children in the country are: rural residents; residents of the East, North and South-West regions; Kaka-Baya and Fulbe-Fulani children; and children whose mothers have no education, are Traditionalists, are unmarried, or are in polygamous unions. Lack of maternal schooling alone explains all the excess childhood mortality of Fulbe-Fulani children, most of the excess mortality of children of the North and East regions, most of the excess mortality of the countryside vis-à-vis the metropolitan areas of Yaoundé and Douala, and most of the excess mortality of children of Traditionalists. The robustness of the excess neonatal mortality of newborns in the East region probably reflects the higher prevalence of tetanus in that region compared to the rest of the country. The study also suggests that the place/region of residence in Cameroon is likely to be a proxy for inequalities in the provision of and/or use of health services.