Just as postsecondary schooling serves as a dividing line between the advantaged and disadvantaged on outcomes like income and marital status, it also serves as a dividing line between the healthy and unhealthy. Why are the better educated healthier? Human capital theory posits that education makes one healthier via cognitive (skill improvements) and noncognitive psychological resources (traits such as conscientiousness and a sense of mastery). I employ the Wisconsin Longitudinal Study (1957-2005) to test the relative strength of measures of cognitive human capital versus noncognitive psychological human capital in explaining the relationship between education and health outcomes among high school graduates. I find little evidence that noncognitive psychological human capital is a significant mediator, but find a relatively significant role for cognitive human capital, as measured by high school academic performance. It is not just higher educational attainment; academic performance is strongly linked to health in later life. (Contains 4 notes and 3 tables.)