Seven groups that have been approved to receive Medicare claims data will soon begin to publicly report information on the quality and cost of health care services provided to Medicare beneficiaries. The data-sharing program, mandated by the Affordable Care Act, is expected to galvanize quality improvement efforts by providing physicians and others with feedback on their performance. In the April/May issue of Quality Matters, we report on what the seven groups plan to do with the Medicare data and take a look at the Wisconsin Health Information Organization, which runs one of the nation's most sophisticated all-payer claims databases.