AbstractThis study explored the effects of union membership versus nonmembership on role based stress (i.e. ambiguity, overload, and interrole conflict), somatic complaints, and on the relationship between role stress and somatic complaints. The data analyzed came from the 1977 Quality of Employment Survey (Quinn and Staines, 1979). Only those respondents (N= 251) who held full‐time nonsupervisory jobs in manufacturing were included in our sample. On the average, relative to nonmembers, union members reported higher levels of ambiguity and interrole conflict, but similar levels of overload and of somatic complaints. Union membership moderated the relationship between overload and somatic complaints. For union members, higher perceived performance of the union was associated with lower perceived stress and strain. We discuss the implications of those findings for further research on the impact of unions on stress, strain, and their interrelationshi