This article provides a review of the literature on the International Organization for Migration (IOM) and serves as an introduction to the JEMS special issue devoted to this organisation. IOM has long been a neglected research topic. Since the 1990s, however, it has experienced substantial growth; its role and visibility in the global politics of migration have increased, which has culminated in IOM's elevation to a UN-related organisation status in 2016. This has spurred growing interest in its history, structure, and activities. The main argument developed in this article is that IOM exemplifies some of the key changes currently taking place in the way international migration is apprehended and governed. This is analysed in terms of four main research issues: (1) the role of IOM in migration politics and its relationship to state sovereignty, (2) IOM's managerial and market-inspired approach to the role of migration in the global economy, (3) IOM's relationship to civil society and the implications of its activities in terms of human rights and humanitarian protection, and (4) IOM's normative influence on the production of knowledge and the way migration is intellectually and politically constructed as a research and policy issue.