The quest to improve the quality and safety of health care has been hampered at times by lack of definitive evidence on effective strategies to improve patient outcomes. This tension between the need to improve care and knowing how to do it has generated extensive debate and resulted in the abandonment of some previously widely used performance measures. In this editorial, the leadership of The Joint Commission proposes a framework for quality measurement that emphasizes measures that would lead directly to improved patient outcomes. Such measures—termed "accountability measures"—should have a strong evidence base, be measurable at the point of care, be closely linked to clinical outcomes, and lack unintended adverse consequences. Under the leadership of Dr. Mark Chassin, The Joint Commission has taken an increasingly active role in promoting quality improvement through annual reports on health care system performance and the launch of The Joint Commission Center for Transforming Healthcare.