Advocates for consumer-friendly public reporting on the performance of health care providers anticipate that, at some point, well-vetted and standardized measures will be widely available to help patients choose clinicians who provide the best care. However, achieving that goal would require assembling standardized data from many sources. Such an effort would raise concerns, including privacy considerations about having a single massive data repository; questions of how such an effort would be funded; and potential misuse of the data. This paper proposes creating a public-private data aggregator that would receive patient and provider data from payers that are deidentified in such a way as to remain useful for consumer-reporting and research purposes. The aggregator could be funded through fees charged to commercial users. Meanwhile, registered researchers putting their methods and findings in the public domain could access the data aggregator for free.