In this chapter, I identify and examine what I take to be the normative foundations of Migration Ethics. In Sect. 1, I argue that those foundations are derived from liberal democratic theory, with the Moral Equality Principle as key. In Sect. 2, I explore the implications of the Moral Equality Principle for Immigration Ethics. I also identify the Rationality Principle, that ethical disputes should be settled by rational argument and evidence. I argue that the force of these two principles places work in Migration Ethics in four possible boxes: (1) immigration controls cannot be morally justified—an open borders position; (2) they can be morally justified, but not by appeal to ideas of nation and nationality as these cannot be rationally grounded; (3) the ideas of nation and nationality can be rationally grounded and so can provide a moral justification for immigration controls; (4) the Rationality Principle must be set aside or compromised in some way in order to provide a moral justification for immigration controls. All work in Immigration Ethics, I suggest, fits into one of these boxes. In Sect. 3, I explore the implications of the fourth approach, examining the extent to which political theorists can endorse the suspension of the rationality requirement in putting forward ethical arguments. Finally, in Sect. 4, I examine future challenges for Immigration Ethics, identifying three in particular: the first is deeper engagement with empirical scholarship; the second is to look at issues of migration outside of the context of the Global North; and the third is to give greater attention to forcible displacement and the range of forms it can take.