Extensive research on occupational differences in the incidence of depression was performed by examining two basic measures of well being, depression and global health, that vary by occupation. The study cohort included 9,281 individuals of whom 48% were women, 74% white, 17% black, and 9% Hispanic. About 20% were members of a labor union. The findings indicate that workers in different occupations and occupational groups differed significantly in terms of depression and global health. Workers in professional and managerial occupations had less depression and better health. However, variations existed within each category. A total of 239 different occupations were represented, distributed across 11 occupational categories. Occupations that involved the operation of machines or transportation equipment tended to have poorer scores. The authors suggest the following factors which may contribute to observed differences. First, occupations vary in terms of hazards in the physical environment encountered by employees. Second, self selection may play a role in observed occupational differences in that a healthy worker effect may come into play. Third, occupations differ in terms of the psychosocial conditions experienced by employees. Fourth, occupations may also differ in factors that have an impact on depression and health but which are not directly part of the psychosocial conditions at the place of work. The findings were consistent with the fact that many types of blue collar workers are at a greater risk for poor health when compared to professional or managerial workers.