This chapter examines how and why states regulate their diasporas, and considers whether and how they should do so. The chapter begins by noting that the extra-territorial components of state policies are relatively overlooked aspects of global migration governance—which tends to be conceived in terms of international relations between migrant-receiving and -sending countries. Drawing on a large comparative study, the first section of the chapter highlights that many states dedicate a portion of the state apparatus—referred to as ‘the emigration state’—to emigration and the diaspora. It identifies four different types of emigration state (engaged, disengaged, paper-only, and incoherent) and describes the main features of each, noting that only ‘engaged’ states exhibit a coherent range of mechanisms relating to the diaspora. The second section of the chapter begins to develop explanatory hypotheses for each type, outlining an agenda for further research. The final section of the chapter evaluates arguments for and against ‘engaging diasporas’ in terms of interests, norms, and global cooperation. Based on this evaluation, it concludes there is a need for more coherence in this area of global migration governance.