Christian missions in colonial Africa have contributed significantly to the expansion of formal education and thereby shaped the continent's long-term economic and political development. This paper breaks new ground by showing that this process depended on local demand for education. It is argued that disagreements over norms, and in particular the struggle over polygamy, which resulted from missions' insistence on monogamy in traditionally polygamous areas, lowered African demand for education. Analyses of geocoded data from historical and contemporary sources, covering most of sub-Saharan Africa, show that the struggle is associated with worse educational outcomes today. Effects are not limited to formal attainments but carry over to informal outcomes, in particular literacy. The findings attest to considerable heterogeneity in missionary legacies and suggest that local conditions should be given greater consideration in future studies on the long-term consequences of colonial-era interventions.