International organisations (IOs) have been increasingly involved in the field of migration policy since the 1990s. While immigration policy remains closely associated with State sovereignty, IOs’ growing involvement has resulted in novel patterns of migration governance that are often referred to as ‘global’, ‘multilevel’ or ‘multilayered’. This chapter surveys the key players in such multilevel migration governance, drawing on IOs and on regional organisations. It provides a historical account of IOs’ role and explores changes since the 1990s, marked not only by substantial developments in IOs’ role in migration policy but also by a fragmentation of their efforts. It sheds light on what IOs do, distinguishing between expertise/discourses and actual practices. A central argument is that IOs’ interventions are characterized by a tension between their role as promoters of global standards in the interests of all parties and their dependency on a handful of Western migration-receiving States in the developed world.