The 2010 Patient Protection and Affordable Care Act was a major legislative achievement of the 111th Congress. This law structurally reforms the US health care system by encouraging universal health care coverage through regulated competition among private insurance companies. When looking at the process for reform, what strikes an observer of US health care policy in the first place is that the Democratic majority was able to enact something in a political field characterized by strong resistance to change. This article builds on that observation. Arguments concentrate on the legislative process of the reform and support the idea that it may be partly explained by considering an evolution of US legislative institutions, mostly in the sense of a more centralized legislative process. Based on approximately one hundred semidirected interviews, I argue that the Democratic majority, building on lessons from both President Bill Clinton's health care reform attempt and the Republicans' strategy of using strong congressional leadership to pass social reforms, was able to overcome institutional constraints that have long prevented comprehensive change. A more centralized legislative process, which has been described as “unorthodox lawmaking,” enabled the Democratic leadership to overcome multiple institutional and political veto players.