This study undertook systematic review of findings from low-income and middle-income countries including cohort studies in Brazil, Guatemala, India, Philippines, and South Africa. Undernutrition was strongly associated, both in the review of published work and in new analyses, with shorter adult height, less schooling, reduced economic productivity, and—for women—lower offspring birthweight. Height-for-age at 2 years was the best predictor of human capital and undernutrition is associated with lower human capital. We conclude that damage suffered in early life leads to permanent impairment.