A nationwide survey of nearly 1,700 hospitals finds that 13 percent are participating in or are planning to participate in, accountable care organizations (ACOs) in the next year. The results also show that hospitals already involved with ACOs are improving the coordination of patient care and doing a better job of ensuring safe transitions among care settings—both hallmarks of the ACO model. At the same time, it’s clear that hospitals will need to strengthen their capacity to undertake population-based care and assume financial risk.