Book excerpt: A key provision of the Affordable Care Act is the establishment of the Medicare Shared Savings Program, which provides incentives for improved quality and efficiency to a new category of provider - the accountable care organization (ACO). The program, slated to begin in January 2012, rewards groups of providers who agree to collaborate to offer more accountable, effective, and efficient care with a share of the savings they achieve. While the prospect of participating in this initiative has generated a groundswell of interest and activity among providers, many issues need to be addressed about the methods that will be used to determine how that accountability is to be achieved, assessed, and rewarded. This report provides recommendations for ensuring the successful implementation and spread of ACOs to achieve the goals of a high performance health system.