This chapter presents the different functions of national state regimes from across a large interdisciplinary literature, with examples and analyses chosen from both Western and non-Western contexts. It examines the policing of circulation, the organising of immigration (mainly for labour purposes), and the governance of emigration. It argues that the combination of these different functions varies in time and place depending on the economic, political and international context. This explains why national state regimes are complex arrangements, in flux and riddled with contradictions, displaying interactions with other national regimes as well as international organisations and migrants’ strategies. The chapter first looks at the definition of national state boundaries and its connection to the control of circulation. Second, it turns to the organisation and selection of migrant workers. Finally, it examines emigration and exit policies.