Micronutrient deficiencies that reduce the health of children risk impeding human capital investments critical for economic development. While the developed world has largely eliminated the most pernicious of these deficiencies, they remain widespread in poorer countries. This study looks at the effects of the introduction of fortified milk, which contributed to the decline of one such micronutrient deficiency in the United States: vitamin D. At the time of vitamin D milk’s introduction in the early 1930s, vitamin D deficiency, manifested most prominently in the form of rickets, affected large numbers of children. Using previously unexamined historical sources, I compile and introduce an original dataset describing the rollout of vitamin D fortified milk across the United States throughout the decade. I then use this dataset to examine the impact of fortified milk on schooling. The gradual expansion of vitamin D milk, along with natural variation in susceptibility to vitamin D deficiency due to geographic and racial factors, permits the identification of fortification’s impact from other regional and temporal trends. Using a difference-in-difference-in-difference (DDD) estimator, I find that the availability of vitamin D milk increased schooling for the group at highest risk for vitamin D deficiency: African-American children from cities with low sunlight. A variety of sensitivity tests supports the validity of the results. They indicate that large scale food fortification initiatives merit further consideration from economists and policy makers concerned with achieving development outcomes.