This policy brief updates a RUPRI Center analysis of the presence of Medicare Accountable Care Organizations (ACOs) in rural areas of the United States in 2013. Using participation data through 2015, the current brief finds that there has been broad growth in the number of places where ACO participating providers can be found. Rural interest in the ACO model is strong, with participating providers found in 41.8% of non-metropolitan counties. A recent Centers for Medicare & Medicaid Services (CMS) fact sheet reported that 65 (15 percent) of Medicare ACOs included at least one participating Rural Health Clinic, and 55 (13 percent) included at least one participating Critical Access Hospital. Clearly, there is rural interest in the ACO program and CMS initiatives like the ACO Investment Model (AIM) – designed to encourage the formation of new ACOs in rural and underserved areas – will enhance the level of interest.