We show that ethnic distances can explain the ethnic inequalities in child mortality rates in Africa. Using individual level micro data from DHS surveys for fourteen Sub-Saharan African countries combined with a novel high resolution dataset on the spatial distribution of ethnic groups we show that children whose mothers have a higher linguistic distance from their neighbours have a higher probability of dying. Fractionalization reduces the probability of child death. We argue that fractionalization reflects a higher stock of knowledge and information leading to better health outcomes. Knowledge does not flow smoothly to linguistically distant groups. Linguistically distant mothers also have a lower probability of knowing about the oral rehydration product (ORS) for treating children with diarrhoea.