The scholarly literature on health care politics has generated a series of hypotheses to explain U.S. exceptionalism in health policy and to explain the adoption of national health insurance (NHI) more generally. Various cultural,institutional, and political conditions are held to make the establishment of some form of national health insurance policy more (or less) likely to occur. The literature is dominated by national and comparative case studies that illustrate the theoretical logic of these hypotheses but do not provide a framework for examining the hypotheses cross-nationally. This article is an initial attempt to address that void by using Boolean analysis to examine systematically several of the major propositions that emerge from the case study literature on the larger universe of twenty advanced industrial democracies. This comparative analysis offers considerable support for the veto points hypothesis while still finding each of the factors examined to be relevant in certain scenarios. We conclude with a discussion of the implications of these findings for future research and for advocates of national health insurance in the United States.