In Minimal Morality, I develop a multilevel social contract theory that, in contrast to existing theories in the liberal tradition, does not merely assume a restricted form of reasonable moral pluralism but is tailored to the conditions of deeply morally pluralistic societies that may include liberal moral agents, non-liberal moral agents and, according to the traditional understanding of morality, non-moral agents. The theory takes its main inspiration from the moral theories of Hobbes (1651), Hume (1739/1740) and Kant (1785, 1795, 1797), and some of their contemporary followers, such as Rawls (1971) and Gauthier (1986). In its simplified form, the theory combines what I call traditional first-level morality with second-level pure instrumental morality and derives, in the form of the weak principle of universalization, a principle of conflict resolution that defines the minimal behavioural restrictions that are necessary to ensure, compared to violent conflict resolution, mutually beneficial peaceful long-term cooperation in deeply morally pluralistic societies. I argue that, despite its ideal nature, this theory is, in principle, applicable to the real world and, for the conditions described, most promising for securing mutually beneficial peaceful long-term cooperation in a world in which a fully just society, due to moral pluralism, is unattainable. If Rawls’s intention was to carry the traditional social contract argument to a higher level of abstraction, then the multilevel social contract theory brings it back down to earth.