How ready are U.S. hospitals and health systems to form accountable care organizations? In the second report in their series, Eugene Kroch and colleagues from the Premier Research Institute discuss results from a recent collaborative involving 59 hospital-based organizations hoping to make the transition to accountable care. In assessing the organizations, the Commonwealth Fund–supported researchers find that health systems' readiness for the transformation to accountable care is "modest," with several characteristics appearing to be associated with higher levels of preparedness. Among these are a strong patient-centered focus, full or partial ownership of a health insurance plan, and positive relationships with providers in the market.