An accountable care organization (ACO) is a healthcare organization that ties payments to quality metrics and the cost of care. ACOs in the United States are formed from a group of coordinated health care practitioners. The ACO adopts alternative payment models (e.g., capitation). The ACO is accountable to patients and third-party payers for the quality, appropriateness and efficiency of its services. According to the Centers for Medicare and Medicaid Services (CMS), an ACO is “an organization of health care practitioners that agrees to be accountable for the quality, cost, and overall care of Medicare beneficiaries who are enrolled in the traditional fee-for-service program who are assigned to it”.