The concept of public service bargain (PSB) has been reintroduced in recent times to the study of public administration to analyse the division of roles between ministers and the civil service in the context of public service reforms (Hood 2000, 2001, 2002; Hood and Lodge 2006). The empirical investigation of the concept of PSB in general and changes in PSBs in particular is, however, limited. This article addresses this limitation by investigating what causes changes in public service bargains, particularly with respect to the provision of advice. As argued by Hood, we demonstrate how changes in PSBs can be explained by a combination of changes in the environments of ministries as well as the interests of the political actors. Furthermore, we point to the professional qualifications of civil servants as well as their interests as causes of change which, until now, have not received sufficient attention in the PSB literature. The article is based on a longitudinal case study of PSB between ministers and the permanent civil service in Denmark.