Using Social Exchange Theory, this study compared the impact of nurses’ workplace relationships with management and colleagues upon nurses’ work harassment, psychological well-being, and engagement within the public and private sectors in both Australia and Italy. Using survey data from 1,587 nurses, SEM findings indicated that public sector nurses in Australia had the lowest satisfaction with supervision, higher work harassment, and lower engagement and psychological well-being, than the other groups. The implications include that poor workplace relationships enable work harassment and therefore management upskilling is required along with changes in performance measures to ensure greater nurse well-being and engagement.