The Accountable Care Organization payment model is growing, so you may not want to wait any longer to figure out how you fit into it. Sixty-five organizations are now participating in the ACO model, CMS says in a release. That includes 32 Pioneer Model ACOs announced last December, six Physician Group Practice Transition Demonstration organizations that started in January 2011, and 27 new ACOs announced April 10. As of April 1, more than 1.1 million beneficiaries are receiving care from providers participating in Medicare shared savings initiatives, CMS says. A list of participating ACOs and program information are at http://innovations.cms.gov/initiatives/ACO/Advance-Payment.