Abstract: Much of Justice Sandra Day O'Connor's work on the Supreme Court embodies a commitment to judicial minimalism, understood as a preference for narrow rulings, closely attuned to particular facts. This preference reflects a belief that at least in adjudication, standards ought to be preferred to rules. In many contexts, however, that belief is hard to justify, simply because it imposes severe decision-making burdens on others and may well create more, rather than fewer, errors. For this reason, a general preference for minimalism is no more defensible than a general preference for rules. The choice between narrow and wide rulings cannot itself be made by rules or even presumptions; it requires a case-by-case inquiry. The argument is illustrated throughout with reference to the problem of affirmative action, where Justice O'Connor's preference for particularity resulted in the imposition of a constitutional mandate on admissions offices that is not simple to defend in principle. In some contexts, however, narrow rulings are indeed preferable, in large part because they give flexibility to politically accountable officials. Justice O'Connor's minimalism is best understood as reflecting a belief that in difficult cases, at the frontiers of constitutional law, judges do best to avoid firm rules that they might come to regret.