The study of immigration/migration in international relations (IR) is, in many ways, a latecomer to the discipline. This is perhaps no great surprise, as the discipline has traditionally focused on questions of stability and war in the international system. However, there are many ways that international migration intersects directly with IR, even traditionally defined, and this has driven a growing body of scholarship. First, migration is itself a function of the international system of states. Without states, there are no borders to cross and it is the crossing of borders that remains at the heart of the politics of migration: who crosses, how, where, and why, are the operative issues at the heart of policymaking, debate, and practice in migration. This also places the state at the heart of much of the analysis; the ability to control borders is at the core of questions of state sovereignty. It is state action, regulation, and law, therefore, that shape and determine much international migration. As many critical scholars have pointed out, however, migrants themselves also have agency and autonomy; their movements are not simply reactive to state policy and practice, but determine its direction. Here, then, we see a manifestation of one of the foundational debates of world politics: which actors have power, and how that power is understood. Further, international migration by its very definition involves more than one state, calling attention to interstate relations, and to questions of bilateral and multilateral cooperation. The emergence of key international institutions, such as the United Nations High Commissioner for Refugees (UNHCR), the International Organisation for Migration (IOM), and the International Labour Organisation (ILO), also brings us questions of institutional power (often versus state power), and of the development of international regimes. Migration studies is located at the intersection of several different disciplines and fields of study. Particularly in critical scholarship, work in geography, sociology, anthropology, political and social theory, economics, and cultural studies have all influenced, and been influenced by, work in IR. Within IR, the key issues of analysis that emerge are a focus on international regulatory frameworks and regimes, issues of governance, questions of cooperation, and the intersections between migration and security. Although IR has often been accused of a Euro- or Western-centric scholarship, important alternative voices emerge within migration studies, and they are represented particularly in scholarship that focuses on refugees and asylum issues.