The first half of the twentieth century saw rapid improvements in the health and height of British children. Average height and health can be related to infant mortality through a positive selection effect and a negative scarring effect. Examining town-level panel data on the heights of school children I find no evidence for the selection effect but some support for the scarring effect. The results suggest that the improvement in the disease environment, as reflected by the decline in infant mortality, increased average height by about half a centimeter per decade in the first half of the twentieth century.