This paper shows that children of mothers who are ethnically more distant from their neighbours have worse health outcomes. I combine individual-level micro data from DHS surveys for 14 sub-Saharan African countries with a novel high-resolution dataset on the spatial distribution of ethnic groups at the 1km×1km1km×1km level. I measure ethnic distance using linguistic distance and construct the spatial distribution of ethnic groups using an iterative proportional fitting algorithm. Using a time-varying ethnicity fixed effects framework to curb unobserved heterogeneity across ethnic groups, I show that children whose mothers are linguistically more distant from their neighbours face higher mortality rates and are shorter in stature. The pernicious effects of linguistic distance are more pronounced in areas where malaria is endemic. I argue that higher linguistic distance impedes the transmission of information. Consistent with this interpretation, mothers who are linguistically more distant from their neighbours are less likely to receive health-related information. Linguistic distances driven by splits that occurred thousands of years ago are more relevant than more recent splits.