A central sociological premise is that health care systems are organizations that are embedded within larger institutions, which have been shaped by historical precedents and operate within a specific cultural context. Although bound by policy legacies, embedded constituencies, and path dependent processes, health care systems are not rigid, static, and impervious to change. The success of health care reform in 2010 has shown that existing regimes do have the capacity to respond to new needs in ways that transcend their institutional and ideological limits. For the United States the question is how health care reform will reconfigure the existing network of public and private benefits and the power relationships between the numerous constituencies surrounding them. This article considers how institutions, interest groups, and ideology have affected the organization of the health care system in the United States as well as in other nations. It then discusses issues for future research in the aftermath of the 2009-10 health care reform debate.