The posting of workers has become a key topic in debates about how national labour relations respond to pressures from EU market making. While most prior studies have shown that national employment relations are under pressure from above (via EU regulation) and from below (due to increasing use of posting), the question is whether these pressures will lead to erosion of employment relations or adaptation at the national level. Taking the case of posting in the Danish construction sector, the article shows that, while formal institutions stay the same through minor adaptation, the increasing use of posting has led to changes in the strategies of the social partners, shifts in predominant policy arenas and the appearance of new actors on the regulatory scene. As such, we argue that conflicts regarding posting are driving a process of extra‐institutional change.