The article provides a comparative analysis of trade union responses to the arrival of CEE workers in Denmark, Norway and the UK, with a special emphasis on the organizing efforts of construction workers’ unions. Organizing has been seen as a crucial element in avoiding a situation where the presence of CEE workers may lead to low-wage competition and social dumping. On the basis of case studies from Copenhagen, Oslo and the North-East of England the article analyses how the unions’ strategies on recruiting migrants were developed, the novelty of these strategies and results when it comes to member ship gains