Given how much harm can be done after the fighting part of wars end, and given recent failures to secure lasting peace after conflicts (e.g. in Afghanistan and Iraq), developing an account of the conditions of a just peace, or jus post bellum, is crucial. Unfortunately, jus post bellum has long been largely ignored by just war theorists. In this dissertation, I present and briefly defend a theory of what morality requires of us after a war, according to which the arrangements that we commonly think parties formerly at war are morally required to institute are actually just the best ways for those parties to compensate each other for the warrelated injustices they have exposed each other to. I call this the compensation theory of jus post bellum. Part of this theory is the claim, which I briefly defend, that any time we violate someone's moral rights, morality requires us to compensate our victims, even if we did so during a war, and were overall morally justified in doing so. By being clear on the moral foundations of jus post bellum, the compensation theory of jus post bellum is helpful both in evaluating the morality of peace settlements, and in settling conflict between competing postwar arrangements. While it focuses on what parties to a war owe each other once the war is over, the compensation theory of jus post bellum does not rule out the possibility that a just peace is everyone's concern. Indeed, parties not involved in a war may well have a moral duty to help prevent harm after the war has ended, or to ensure that the compensation that the compensation theory of jus post bellum claims is owed is given. What these universal duties are is a promising area for future research. If true, the compensation theory of jus post bellum has some interesting implications for what morality demands of states during wars, as well as for what international law (which should at least partly reflect morality) should look like. First, it entails that a just peace may require just victors to compensate their defeated opponents. Given that even states that go to war justly do not always fight justly, and that wars almost inevitably involve harm to bystanders and innocents, this should not be too surprising. But it bears repeating, as just victors have a tendency to think that they owe their enemies little. Second, the compensation theory of jus post bellum entails that attempts to overpower one's enemy with superior firepower is morally costly. This is because such attempts typically involve innocents being exposed to collateral damage, which they then have to be compensated for. More measured, targeted strategies are morally preferred. Lastly, accepting the compensation theory of jus post bellum means paying much more attention to what countries at war do to their own citizens. Wartime emergency measures are common, and can be horrific. Unfortunately, they are sometimes treated as an internal, political issue, rather than an issue of wartime justice, on par with the other principles of just war. According to the compensation theory of jus post bellum, internal wartime measures that infringe rights are wartime injustices like any other, and the victims of such measures are owed compensation for their injustices. Compensating for such injustices, and preventing future ones, is thus not merely a matter of politics or social stability, but a matter of justice.