The National Survey of Mid-life Developments in the United States (MIDUS) is one of several studies that demonstrate socioeconomic gradients in mortality during midlife. When MIDUS findings on self-reported health, waist to hip ratio, and psychological well-being were analyzed for their possible roles in generating socioeconomic differences in health, they revealed clear educational gradients for women and men (i.e., higher education predicted better health). Certain potential mediating variables, like household income, parents' education, smoking behavior, and social relations contributed to an explanation of the socioeconomic gradient. In addition, two census-based measures, combined into an area poverty index, independently predicted ill health. The results suggest that a set of both early and current life circumstances cumulatively contribute toward explaining why people of lower socioeconomic status have worse health and lower psychological well-being.