The next steps in health reform, like all such efforts before it, will have to engage the issue of American health care federalism – the relationship between the federal and state governments in the realm of health law and policy. Since its enactment in 2010, the Patient Protection and Affordable Care Act (ACA) has offered a robust example of modern federalism and revealed new complexities. This article recounts the findings of our five-year study of the federalist and nationalist features of ACA implementation. Contrary to the claims of ACA opponents that the law marked a federal “takeover,” the ACA's governance structures have advanced rather than suppressed state power. But we also found that the advances in state power occurred seemingly independently of the statute's structural arrangements; that is, the ACA's nationalist and federalist features both enhanced state power over health policy. These findings raise questions about whether cherished American federalism values are unique to federalist structures; they also raise the question of what exactly health care federalism is for, and why we continue to design health policy with federalism front and center. It is not clear that enhanced state power has brought better health policy. If it has not, is federalism for its own sake worth the trade-off?