A number of different diseases have been related to psychosocial conditions in the workplace, most notably coronary heart disease (CHD), musculoskeletal disorders, and mental illness. This chapter addresses two types of questions: the relation between conditions at work and disease; and the contribution this relationship may make to the explanation of variations in disease in society. It argues that two theoretical models hold particular promise in explaining at least part of the social variation in disease, and especially CHD — a variation that may be attributed, in part, to work stress as defined by the demand-control and effort-reward imbalance models. High demand/low control conditions and high cost/low gain conditions at work are unequally distributed both between and within societies, and may potentially provide a framework in which to understand the contribution of psychosocial factors at work to the development of disease.