Theoretical arguments highlight the importance of Public Service Motivation (PSM) in underpinning employment relationships in the public sector, mainly based on the presumption that many aspects of public service provision are non-contractible. Consequently, hiring workers who are public service, or pro-socially, motivated helps to overcome incentive problems and to increase organizational efficiency, thus reducing the need for high-powered incentives. However, such an argument would be undermined should workers' pro-social or intrinsic motivation dissipates rapidly with job tenure. Based on longitudinal data from the British Household Panel Survey (BHPS), we explore patterns of overall and domain satisfaction measures for workers who made the transition from private to public sector employment. We are particularly interested in finding out whether any possible boost in satisfaction with the nature of the work itself, our proxy for pro-social or Public Service Motivation (PSM), associated with accepting public sector employment dissipates following the transition into public sector employment. Our results reject the hypothesis of a rapid and complete adaptation of PSM back to baseline or pre-transition levels. Interestingly, this is not the case for public to private or for within-sector transitions, which result in a short-lived increase in intrinsic motivation. This is welcome evidence for the advocates of the benefits of having pro-socially or intrinsically motivated people working in the public sector.