Given the long struggle to enact health care reform in the United States, the passage of such significant reform in 2010 — the Patient Protection and Affordable Care Act (ACA) — has prompted many seasoned political analysts to consider these questions: What was different this time? How did this reform pass when so many other attempts have failed? Political scientists Lawrence D. Brown, Mark A. Peterson, and Jacob S. Hacker each offer conceptual frameworks for understanding the passage of the ACA. From these, we turn to essays that examine particular factors that influenced the passage of the ACA. Joseph White focuses on the legislative need to build a Democratic coalition and the political dangers of accommodating the median legislator — in this case, the Blue Dog Democrats. Jill Quadagno examines the multifaceted role of interest groups in shaping the ACA. James Brasfield considers the evolution of the public option in the larger politics of health reform. Federalism, as that ever-important institution in U.S. health care policy, has been no less important in shaping the passage of the ACA. Michael S. Sparer shows us how intergovernmental politics interacted with interest-group politics, political culture, and institutional grid-lock as various bills wound their way through Congress, leading to the ultimate passage of the ACA. Scott L. Greer considers the role of states under the ACA and argues that this new framework — increased federal financing and regulation combined with substantial state flexibility — has the potential to be a dramatic improvement over the status quo. That improvement, however, will depend on intergovernmental politics and states' willingness to participate.