THE U.S. HOSPITAL SYSTEM SUFFERS FROM SHORTFALLS in quality and from unsustainable growth in costs. The 2000 Institute of Medicine (IOM) report To Err Is Human documented major weaknesses in the quality in hospital and ambulatory settings; the 2001 follow-up report, Crossing the Quality Chasm, laid out a vision of a health system that delivered safe, reliable, timely, and patient-centered care.1 Improving the quality of America’s hospitals has become a highly visible public and private enterprise, as payers, accreditors, and private organizations attempt to set standards and encourage their achievement.