To what extent is voter turnout influenced by ethnic inequality? We combine ethnolinguistic maps on sub-national locations of ethnic groups with night-time light satellite images to construct a dataset of ethnic inequality across sub-national locations in 24 African countries. Using election data from the constituency-level elections archive, we show that ethnic inequality is negatively associated with voter turnout. This relationship holds even after we control for endogeneity and geographic characteristics. We also construct a dataset of election conflict across the sub-national areas. We find that an increase in ethnic inequality is associated with an increase in conflict, which reduces voter turnout.