Whereas the impact of trade relations on conflict has been studied extensively, this is not the case for the impact of international migration. The latter might influence the size of expected costs and benefits, and hence the likelihood of military conflict between countries. In this paper, we discuss the channels through which bilateral migration can affect the prevalence of interstate military conflict. We then estimate migration’s impact on conflict using bilateral panel data between 1960–2000. We find evidence of a positive and robust impact of South-North and South-South migration on the occurrence of conflict. These effects are even larger when we control for potential endogeneity using a GMM approach.