This study aimed to test longitudinal associations linking the work-unit-level psychosocial and orga- nizational work environment and biomechanical constraints to workers’ shoulder pain in the French multi-centre cohort ORSOSA study of registered nurses (RN) and nursing assistants (NA). We analyzed 1896 female RN and NA, who were free of shoulder pain in 2006 and in the same position and work unit in 2008. Incident shoulder pain (SP) was de ned as self-reported pain that persists for ≥4 days and/or increases during a lateral movement of the arm away from the midline of the body (abduction). Both cross- sectional and longitudinal models were built to test if work-unit-level features or their in uences on both work tasks and individual perception of the work environment directly in uence the risk of developing incident SP. RN in work units with understaffing issues or poor relationships reported higher levels of biomechanical constraints in movements and postures and a lower level of perceived job security and stability. NA who experienced such issues reported higher levels of biomechanical constraints in indirect patient-handling activities only. The exposure to these latter factors was associated with higher two-year incident SP among workers. This study shows that the work-unit-level organizational characteristics may impact workers’ musculoskeletal disorders by conditioning both work-task-related biomechanical exposures and individual perception of the working environment. In healthcare settings, primary prevention programs to reduce MSD would benefit from a focus on work unit level exposures.