If the potential of accountable care organizations (ACOs) is realized, they could significantly transform how health care is delivered and financed, bringing the promise of high-quality affordable health care within reach. This article explores the root causes that have handicapped the value in the health care delivery system historically and the critical requirements to overcome those issues. The authors describe how commercial and Medicare ACOs attempt to address those issues, the potential land mines in the transition to a new paradigm and the principles plan sponsors should consider in understanding and integrating ACOs into their health care benefits strategy.