How much does disease depress development in human capital and income around the world? I discuss a range of micro evidence, which finds that health is both human capital itself and an input to producing other forms of human capital. I use a standard model to integrate these results and suggest a reinterpretation of much of the micro literature. I then discuss the aggregate implications of micro estimates but note the complications in extrapolating to general equilibrium, especially because of health's effect on population size. I also review the macro evidence on this topic, which consists of either cross-country comparisons or measuring responses to health shocks. Micro estimates are one to two orders of magnitude smaller than the cross-country relationship but nevertheless imply high benefit-to-cost ratios from improving certain forms of health.