The Contingency of Moral Personhood challenges conceptions of the person on which moral personhood is an inviolable feature of the human condition. In its place, I argue for a novel account of moral personhood in which having the status as an end in oneself is contingent on the social and political factors of one’s environment. By investigating the moral psychology of living under conditions of oppression, I argue that its distinct interpersonal trauma has the potential to transform full moral beings, ends in themselves, into mere means for the advancement of others’ ends. Furthermore, I argue that this is a moral-metaphysical transformation and not merely a distortion in victims’ moral self-understanding. This moral vulnerability is at the heart of what it is to be human, and our ethical theories must be revised on account of it. Further, I expand this idea into political philosophy, and argue that theories of justice containing inviolability conceptions of the person will fail to account for the contingency of moral personhood, and thereby fail to articulate principles that fully capture the injustice of oppression. Finally, I argue that consideration of the contingency of moral personhood reveals that revenge is a rational moral motivation under conditions of oppression where the requirements of justice have not been met. Rejecting those accounts of revenge that view it as both irrational and morally objectionable, I instead develop a view on which the act of revenge is also an interpersonal act of moral emancipation.