In recent years welfare services in Western Europe have been criticized for poor coordination. In response, 'seamlessness' has emerged as a vision for public administration with 'one-stop shops' viewed as means to reach this. This article conceptualizes the one-stop shop and presents a three country case study to examine its drivers and its adaptation. In all countries the reforms meant mergers driven by hopes for a single entrance to services as well as proximity to citizens. However, the analysis of task portfolios, participant structure, instruments and autonomy reveal important variations in the adaptations. The specific configurations of one-stop shops that emerged were partially a product of compromises and negotiations influenced by the political and performance priorities of central government. The classical trade-off between specialization and coordination persists, but by offering users ICT-based services one can to some extent maintain specialization behind the frontline and still provide services that are coordinated from a user perspective. © 2011 Blackwell Publishing Ltd.