Although health care systems around the world are undergoing rapid changes, there is an absence of comparative studies of how these changes affect nurses’ well-being and work life. The purpose of this study was (i) to identify and describe possible differences between the psycho-social work environments of English and Swedish mental health nurses, and (ii) to attempt to explain these differences. 1016 psychiatric nurses from Stockholm (Sweden) and Birmingham (England) responded to a postal questionnaire on their psycho-social work environment and feelings of professional fulfilment, mental energy and work-related exhaustion. The study was given ethical clearance in Stockholm and Birmingham. Results indicated that while the English nurses rated their organizational well-being more favourably, Swedish psychiatric nurses reported greater individual well-being than their counterparts. Multiple regression analyses indicated that self-esteem was important for explaining mental energy and work-related exhaustion, but less so for explaining professional fulfilment, which was predicted primarily by organizational factors. When controlling for self-esteem, which was higher amongst the Swedish nurses, the differences in professional fulfilment and mental health were no longer significant. Reasons for the differences in self-esteem and experiences of the workplace are discussed. Low response rate may have contributed to a selection bias.