This chapter reviews and evaluates the main arguments for and against diaspora engagement policies. It examines the equally common normative argument that migrant-sending states have obligations to treat their diasporas fairly. The chapter also considers the increasingly widespread argument that better 'diaspora governance' is required to enhance international cooperation in the area of migration. It reviews and evaluates prominent arguments surrounding diaspora engagement policies, focusing on three main areas: the interests of states, the mutual obligations between states and emigrants, and the cooperation between sending states, receiving states and migrants themselves. The chapter has shown that migrant-sending states are confronted with imperatives and opportunities to pursue their interests through engaging their diasporas, but that these arguments alone do not necessarily override the territorial norm around which world politics are theoretically organized.