We argue that the United States does not have comprehensive national health insurance (NHI) because American political institutions are biased against this type of reform. The original design of a fragmented and federated national political system serving an increasingly large and diverse polity has been further fragmented by a series of political reforms beginning with the Progressive era and culminating with the congressional reforms of the mid-1970s. This institutional structure yields enormous power to intransigent interest groups and thus makes efforts by progressive reformers such as President Clinton (and previous reform-minded presidents before him) to mount a successful NHI campaign impossible. We show how this institutional structure has shaped political strategies and political outcomes related to NHI since Franklin D. Roosevelt. Finally, we argue that this institutional structure contributes to the antigovernment attitudes so often observed among Americans.