Accountable care organizations (ACOs) have befuddled imagers, with radiologists wondering how the specialty might fit into a model seemingly focused on primary care. ACOs have been a hot topic for several years, and generate many unanswered questions. How will the model differ from health maintenance organizations? What methods will they use to cut spending? The answers remain elusive, but with more than 200 ACOs in various stages of operation in the U.S., its time for radiologists to take charge of defining imagings role in the ACO model.