The contribution of the disposition known as locus of control beliefs to the job demands/worker health relationship was examined. Locus of control refers to the belief that life's events are either controlled by the actions of the individual (internal) or by outside forces (external). A foundation of the locus of control concept is that behavior in a specific situation is a function of expectancy and reinforcement value. Locus of control plays a part in job aspirations and expectations with those who feel that control is external having lower expectations for satisfaction and a greater discrepancy between what they would like in a job and what they actually expect to get. Internals appear to have higher expectations about the relationship between effort and job performance, and between performance and rewards. Role ambiguity at work has been linked significantly with high tension at work in middle managers classified as externals. Externals reported more job satisfaction under low, rather than high, ambiguity. Externals are thought to experience more adverse health outcomes because they define events in their lives as outside of their control, and believe that their actions will have little influence on the stressors. In contrast to other life area stressors, workplace stressors may be less likely to be under the control of the individual. Examples of stress include workload, workpace, autonomy, lack of participation in decision making, deadlines, role conflict, ambiguity of roles, and shift work. Coping is ineffective when the stressor is uncontrollable and an internal locus of control may be of questionable benefit to persons in certain work settings. The author concludes that additional research is needed to determine the stability of the locus of control construct, and to identify the path through which locus of control influences worker health.