Because of a perceived decline in staff morale, the UK National Health Service (NHS) has begun to routinely assess the extent to which commitment to the NHS may aid in staff retention. While a number of studies have investigated the role of employee commitment in relation to staff turnover, no research to date has empirically tested if staff commitment to the NHS could protect job satisfaction from the effects of high job demands, and if this varies according to age. Using latent variable path analysis, this novel study examined this question among a national sample of Healthcare Professionals Allied to Medicine (AHPs) in the NHS. The results indicate that the negative effects of high job demands on job satisfaction were fully mediated by commitment to the NHS, but age mattered. Among the over 45's and over 55's, commitment to the NHS acted as an effective buffer against the negative effects of job demands on job satisfaction, but it this effect was not as strong among the 35-44 age group. The broader policy implications of these findings are that age sensitive policies to support workforce retention are needed. Also, pro-social institutions who employ AHPs should develop policies for inspiring commitment to that institution, as it could help then with the demands of the job and may even encourage more skilled workers to work longer.