This study estimates the impact of childhood malnutrition on educational achievement among Peruvian children. While there is growing evidence in the literature that a child’s nutrition is important for his or her own educational development, this paper will focus on the nuances of what type of nutritional status, and at what stage of childhood, is most critical for educational achievement. The data used in this study comes from a longitudinal survey in Peru conducted by Oxford University’s Young Lives project. This study accounts for the potential endogeneity and measurement error in the child anthropometric measures by using instrumental variables approach.