Several recent studies have made the provocative claim that income inequality is an important determinant of population health. The primary evidence for this hypothesis is the repeated finding—across countries and across U.S. states— that there is an association between income inequality and aggregate health outcomes. However, most of these studies examine only a single cross section of data and employ few (or even no)control variables. We examine the relationship between income inequality and aggregate health outcomes across thirty countries over a four-decade span and across forty-eight U.S. states over five decades. In large part, our findings contradict previous claims.