This article examines the potential confounding of observed relations between shiftwork and health outcomes by differences in the jobs typically carried out by shiftworkers and dayworkers. Objective factors (daywork vs. day/night shiftwork and job type) and work perceptions (job demand, discretion, social support, and physical stressors) were analyzed as joint predictors of psychosomatic complaints (headaches and musculoskeletal, gastric, and sleep problems), affective distress, and work-related injuries in data from oil industry personnel (N = 1,462). Logistic regression showed that, after control for individual differences (including age and negative affectivity), shiftwork and job type each predicted specific health outcomes when evaluated simultaneously. Work perceptions also contributed significantly to each outcome, partially mediating relations between job type and health.