A study assessed the relation of potentially stressful objective job characteristics and perceived psychosocial job stress and the relation of both of these to a variety of indicators of physical and mental health. The study also determined whether any of these relationships were conditioned by a variety of individual characteristics (age, education, work motivations, and personality traits) and situational characteristics (social support, exposure to physical-chemical hazards, and piecework). Data were collected from a self-administered questionnaire sent to 2,856 workers (67 percent of whom completed the questionnaire) in a tire, rubber, plastics, and chemical plant in a small northeastern city and from limited medical examinations of a subset of 353 of the 1,809 white male respondents. Included among the major study findings were the following: (1) a wide range of perceived occupational stress was associated with both reported symptoms and medical signs of ill health; (2) while job characteristics were related to perceived stress in the predicted ways, the relationships were weaker than expected; and (3) two conditioning variables (exposure to physical-chemical hazards and social support) had strong and important effects. Limitations of the study were noted and discussed. (MN)