It is hardly a secret that the American health care industry is in a state of flux. Over the past few years, numerous innovative proposals claiming to increase access, to reduce costs, or to do both, have been floated. Some of these innovations made their way into the Patient Protection and Affordable Care Act (PPACA), widely known as Obamacare, which became law in 2010 but has yet to take full effect. As a result, health care providers—along with their patients, investors, strategic advisors, and legal counsel—are struggling to understand the new terrain. This brief article outlines some considerations of one body of law relevant to one PPACA innovation: the antitrust implications of Accountable Care Organizations (ACOs).