Proceedings of a 2 day interdisciplinary symposium on the relationship between shift work and worker health and well being, sponsored by NIOSH, were presented. The goals of the symposium included arriving at an understanding of the social, psychological, and physical effects of shift work, and identifying optimum schedules to be recommended to industry to minimize recognized negative effects. Research papers on circadian rhythms, desynchronization in phase shifting, toxicological correlates of shift work, accidents and injuries related to shift work, and social and psychological adjustment problems related to shift work were presented. Individual differences in ability to adapt to shift work were emphasized. Methodological problems encountered in research on health and shift work were discussed, and designs for future investigations were suggested. Areas in need of further research were identified and guidelines for fulfilling these research needs were provided. The need for cooperation between management and employees in optimizing shift work schedules was stressed.