The Centers for Medicare and Medicaid Services (CMS) announced on July 7 that its Web site at www.hospitalcompare.hhs.gov has been expanded to include key measures and hospital-specific data on outpatient and emergency care delivered to Medicare beneficiaries. This supplements inpatient hospital care measures and data long available on the site as well as some recently upgraded inpatient data, offering consumers and researchers a stronger empirical foundation to compare each Medicare participating hospital to its in-state peers and to US norms. The CMS measures include clinical processes and procedures, treatment outcomes, use of medical imaging, and the findings of consumer satisfaction surveys. Data reported on 4,700 US hospitals for the period July 1, 2006 to June 30, 2009 show wide variations among comparable acute care hospitals on some measures, such as in the extent and patterns of medical imaging use (CT scan, MRI, and mammography overuse and underuse). States can align CMS Medicare data for individual hospitals with Surveillance and Utilization Review Subsystem (SURS) provider profiles and exception ranking reports from their Medicaid Management Information Systems (MMIS) to analyze variations in cost, utilization, and quality among hospitals in peer groups across both programs. CMS encourages rigorous statistical analysis and appropriate clinical engagement in the use of these tools. A recent University of Pennsylvania study of 3,400 hospitals shows improvements in key measures (some related to readmissions and mortality) since CMS began systematically making hospital-specific performance data available in 2005.