This article draws on interviews, register data and a survey with 150 Polish posted workers in the Danish construction sector to analyse the challenges of enforcing the labour rights of posted workers. It argues that while posting companies are generally more ‘unruly’ vis-a-vis host country institutions, their way of engaging with these institutions varies depending on whether the company is a main contractor, subcontractor, or a private home service provider. This implies that the enforcement challenges that union and labour inspectors face differ just as the conditions of posted workers vary depending on the employer’s position. The article concludes that while recent reforms to the rules of posting may solve some legal issues, there are still major challenges on the enforcement front.