The literature on policy implementation is divided with regards to the impact of street-level bureaucrats on the implementation of public policies. In this paper, we aim to add to and nuance these debates by focusing on ‘institutional work’ – i.e. the creation, maintenance and disruption of institutions – undertaken by central authorities and street-level bureaucrats during public reform processes. On the basis of a case study of the organisational implementation of a retirement pension reform in the Norwegian Labor and Welfare Administration, we argue that institutional work is a useful heuristic device for conceptualising the variety of responses available to street-level bureaucrats during public reforms. We also argue that the responses demonstrate the impact of street-level bureaucrats in these reforms in the context of managerial control and regulation. Finally, we argue that the effectiveness of policy change is dependent on the institutional work of street-level bureaucrats and, in particular, on institutional work that supports the institutions created by politicians and public administrations.