Wise management of health care resources is a core tenet of medical professionalism. To support physicians in fulfilling this responsibility and to engage patients in discussions about unnecessary care, tests, and procedures, in April 2012 the American Board of Internal Medicine Foundation, Consumer Reports, and nine medical specialty societies launched the Choosing Wisely campaign. The authors describe the rationale for and history of the campaign, its structure and approach in terms of engaging both physicians and patients, lessons learned, and future steps.In developing the Choosing Wisely campaign, the specialty societies each developed lists of five tests and procedures that physicians and patients should question. Over 50 specialty societies have developed more than 250 evidence-based recommendations, some of which Consumer Reports has "translated" into consumer-friendly language and helped disseminate to tens of millions of consumers. A number of delivery systems, specialty societies, state medical societies, and regional health collaboratives are also advancing the campaign's recommendations. The campaign's success lies in its unique focus on professional values and patient-physician conversations to reduce unnecessary care. Measurement and evaluation of the campaign's impact on attitudinal and behavioral change is needed.