Accountable Care Organizations (or ACOs) are entities that bring together groups of providers to coordinate care for defined populations of patients, are rewarded for their efficient use of resources, and can report meaningful data on their clinical, financial and quality performance. Now what does that mean? On this page, find out what an ACO really is and where they are developing in California, find a description of the Medicare "Shared Savings Program" created by Health Care Reform and now delineated in proposed regulations, and find links to available resources on ACOs.