Overview: The three federal agencies — Centers for Medicare and Medicaid Services (CMS), the Federal Trade Commission (FTC), and the Office of Inspector General (OIG) of the Department of Health and Human Services (HHS) — most likely to become entangled in legal disputes over accountable care organizations (ACOs) hosted a workshop on ACOs on October 5, 2010. Representing these agencies were CMS Administrator Don Berwick, M.D., FTC Chair Jon Liebowitz, and HHS Inspector General Dan Levinson. The three key regulators vowed to work together to promote ACOs and the integration of care made possible by ACOs as ACOs are described in the 2010 health reform law, the Patient Protection and Affordable Care Act (PPACA). They each professed concern over the inhibiting effect that inconsistent enforcement could have on innovative providers who test new models of care. Each regulator must manage and consider means to overcome the unique legal and regulatory hurdles created by their own laws and regulations. This article summarizes some key points from this workshop.