The health community relies on governmental survey, surveillance, and administrative data to track epidemiologic trends, identify risk factors, and study the health care delivery system. Since 2009, a quiet 鈥渙pen data鈥� revolution has occurred. Catalyzed by President Obama鈥檚 open government directive, federal, state, and local governments are releasing deidentified data meeting 4 鈥渙pen鈥� criteria: public accessibility, availability in multiple formats, free of charge, and unlimited use and distribution rights.¹ As of February 2014, HealthData.gov, the federal health data repository, has more than 1000 data sets, and Health Data NY, New York鈥檚 health data site, has 48 data sets with supporting charts and maps. Data range from health interview surveys to administrative transactions. The implicit logic is that making governmental data readily available will improve government transparency; increase opportunities for research, mobile health application development, and data-driven quality improvement; and make health-related information more accessible. Together, these activities have the potential to improve health care quality, reduce costs, facilitate population health planning and monitoring, and empower health care consumers to make better choices and live healthier lives.