A half century of contemporary research documents a graded association between one’s relative economic position and physical and mental health vulnerability risk. These determinants, commonly conceptualized as socioeconomic status (SES) represent one of the most robust psychosocial determinants of physical and mental health and well-being. Importantly, this relationship is graded such that as SES decreases so does health, including risk of early mortality. This chapter begins by reviewing the nature of SES as an amalgam of multiple inter-related yet unique factors and associated measurement strategies followed by a discussion of the contemporary literature demonstrating the relationship between these measured variables and physical health. We then review mediating pathways including health behaviors, environmental factors, and psychophysiological processes. The chapter concludes with a discussion of emerging issues, including the relative effects of SES at different points in the life course at exceptions to the gradient.