Does the extent or lack of progress toward nuclear disarmament affect the health of the nuclear nonproliferation regime? Commentators have long asserted both positive and negative responses to this question as if the answer were self-evident. Given that opposite positions have been advanced with equal conviction, a more systematic analysis is required. This analysis begins by attempting to identify all of the potential arguments that can be made both for and against the hypothesis of a disarmament-nonproliferation linkage. The arguments are grouped in terms of five broader sets of explanatory factors: security, institutions, norms, domestic politics, and psychology. This approach clarifies the various causal microfoundations that could underpin different arguments in the debate as well as the types of empirical tests that would be most relevant for evaluating the “linkage hypothesis.” Comparative assessment of the arguments on both sides suggests that signs of commitment to nuclear disarmament by the nuclear weapon states will tend to enhance support for nonproliferation. Because of the multitude of other factors that affect state decisionmaking, however, progress on disarmament will not by itself address all of the challenges to making the nonproliferation regime effective.