This chapter provides a summary and critical analysis of the three dimensions that constitute the unique labour migration space in the European Union. It appraises scholarly workon the characteristics and effects on labour migration of intra-EU mobility, of EU level policies towards third country nationals and of national level policies towards third country nationals. The chapter finally analyses the complex dynamic of complementarity and substitutability between national and EU level labour migration policies, the interdependencebetween EU legislation governing the free movement of EU citizens, and EU legislation governing the admission ofthird country national workers, and the demand-driven nature of both EU and national labour immigration policies, which are argued to shape patterns on migration across the European Union.