This study examines the effects of supervisor support and coping on work/non-work conflict and health in shiftwork. It describes a model of shiftwork tolerance that is tested on samples from two populations of shiftworkers. The samples--of nurses and ambulance workers--differed by occupation, gender and shift schedule. Quantitative (survey questionnaire) and qualitative methods (in-depth interviews) were used to triangulate results and to yield richer data on psychosocial variables. Structural equation modelling, using EQS, was used to describe the common path relationships observed within both samples of shiftworkers. The results demonstrated important relationships between social support from supervisors, coping strategies, work/non-work conflict and symptoms that transferred robustly between the two populations of shiftworkers.