John E. Wennberg, M.D., M.P.H., is director of the Center for the Evaluative Clinical Sciences at Dartmouth Medical School. He has been a professor in the Department of Community and Family Medicine since 1980 and in the Department of Medicine since 1989, and currently holds the Peggy Y. Thomson Chair for the Evaluative Clinical Sciences. With colleague Alan Gittelsohn, he developed a method of determining population-based rates for the utilization and distribution of health care services. This method, called small area analysis and first published in 1973, revealed large variations in health-care usage among different areas. Work to uncover the reasons behind these variations led Wennberg and his colleagues to develop techniques to document the results of common medical practices, a strategy that came to be called outcomes research. In addition to his work on the Dartmouth Atlas of Health Care, he is also exploring the use of interactive video technology to inform patients of the results of outcomes research so they can participate in medical decision-making. Wennberg received his medical degree from McGill University Faculty of Medicine and his master of public health degree from Johns Hopkins University Bloomberg School of Public Health.