How strong are normative prohibitions on state behavior? We examine this question by analyzing anti-nuclear norms, sometimes called the “nuclear taboo,” using an original survey experiment to evaluate American attitudes regarding nuclear use. We find that the public has only a weak aversion to using nuclear weapons and that this aversion has few characteristics of an “unthinkable” behavior or taboo. Instead, public attitudes about whether to use nuclear weapons are driven largely by consequentialist considerations of military utility. Americans’ willingness to use nuclear weapons increases dramatically when nuclear weapons provide advantages over conventional weapons in destroying critical targets. Americans who oppose the use of nuclear weapons seem to do so primarily for fear of setting a negative precedent that could lead to the use of nuclear weapons by other states against the United States or its allies in the future.