In the mid 19th century, pre-colonial Korea under the Joseon dynasty was increasingly isolated and lagging behind in its economic development. Joseon Korea was forced to sign unequal treaties with foreign powers as a result of which Christian missionaries entered the country and contributed to the establishment of private schools. We show that areas with a larger presence of Christians have higher literacy rates in 1930, during the Japanese colonial period. We also show that a higher number of Protestants is associated with higher female literacy, consistent with a stronger emphasis on female education in Protestant denominations.