The labour market presence of temporary migrant workers in EU member states, coming both from other EU member states and outside its borders has increased dramatically since 2020 (Eurostat). Migrant workers have begun to appear in locations and in jobs where they haven’t been seen before, mainly in poorly remunerated and precarious jobs. The magnitude of the change is partly obscured by the invisibility of this workforce. Part of the attraction of this workforce for employers is its frequently circular, short-term and precarious nature, which also limits its visibility to mainstream society in host countries. It often occurs outside ‘normal’ labour migration pathways, ‘normal’ in this context meaning the regular organized visa and migrant integration systems that regulate migration. This does not necessarily mean the migrants are undocumented: there are a variety of legal frameworks that regulate third country labour migration, and inter-EU migration is of course regulated under EU free movement principles. However, this migration is shaped by employers and other fragmented constellations of actors, rather than host country regulation per se, creating pressure on national labour market norms and industrial relations systems, sometimes challenging them directly but more often undermining them by circumventing them. Temporary migrants are often vulnerable to exploitation, due to the nature of their work contracts, precarious residence status, poor access to social protection, and weak links to host country trade unions and civil society. The systems by which they are recruited and their labour process is managed tend to reproduce these sources of vulnerability, rather than alleviate them.