General internists need to take an active leadership position in the creation of accountable care organizations (ACOs). The basic idea behind ACOs is relatively simple. Physicians, hospitals, and other health care providers will continue to be paid fee-for-service by the Medicare program, but if they can work together to better manage people with chronic conditions, reduce avoidable complications, reduce unnecessary specialty referrals, and improve transfer of beneficiaries as they transition from one care provider to another; then there is the possibility of shared savings with the Medicare program. ACOs are likely to alter existing referral patterns among general internists and specialty physicians and engender debates over how to allocate any financial savings. They are scheduled to begin operation on January 2012. As ACOs are established, general internists should review the operation of the care management and disease management programs. They should understand the financial arrangements and quality indicators that the ACOs establish. They should be involved in identifying the patients that would benefit from better care management. They should identify changes in care processes and payment reforms that would improve the care for these patients. ACOs represent an opportunity for general internists to change the way medical care is delivered.