Virtue ethics is frequently billed as a remedy to the problems of deontological and consequentialist ethics that Bernard Williams identified in his critique of “the morality system.” But how far can virtue ethics be relied upon to avoid these problems? What does Williams’s critique of the morality system mean for virtue ethics? To answer this question, we offer a more principled characterisation of the defining features of the morality system in terms of its organising ambition—to shelter life against luck. This reveals the system to be multiply realisable: the same function can be served by substantively different but functionally equivalent ideas. After identifying four requirements that ethical thought must meet to function as a morality system, we show that they can also be met by certain constellations of virtue-ethical ideas. We thereby demonstrate the possibility of virtue-ethical morality systems raising problems analogous to those besetting their deontological and consequentialist counterparts. This not only widens the scope of Williams’s critique and brings out the cautionary aspect of his legacy for virtue ethics. It also offers contemporary virtue ethicists a more principled understanding of the functional features that mark out morality systems and lie at the root of their problems, thereby helping them to avoid or overcome these problems.