The paper explores the long-term developmental legacies of Protestant missionary involvement in colonial India, specifically missionary effects on male-female inequalities in educational attainment. Our causal mechanisms draw on studies in the sociology and economics of religion that highlight the importance of the dynamics of religious competition for the provision of public goods. We argue that missionaries played a key role in the development of mass female schooling because of the competition among rival religious and secular groups that they spurred in education provision. We explore these causal mechanisms in a case study of the state of Kerala, and statistical analysis covering most of India's districts. For the statistical analysis, we assembled original district-level datasets covering colonial and post-colonial periods. Our data allow us to establish whether missionary effects hold after we account for other factors hypothesized to have a bearing on human development like British colonial rule, modernization, European presence, education expenditures, post-colonial democracy, Islam, caste and tribal status, and land tenure. Our analysis reveals that colonial-era Christian missionary activity is consistently associated with better female education outcomes in both the colonial and post-colonial periods.