Accountable care organizations (ACOs) were originally developed as a Medicare construct as part of the Patient Protection and Affordable Care Act (PPACA) to improve care coordination and lower the cost of care. But four years after the launch of the Medicare ACO program, the ACO construct has been widely adopted by health plans across all payers. There are now over 750 public and private ACOs in all 50 states – including 460 Medicare ACOs, 316 Commercial ACOs, and 62 Medicaid ACOs. It is estimated that between 15% and 17% of the population receive care through ACOs, and 67% of Americans live . . .