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.