Kenneth J. Rothman, DrPH, is a Distinguished Fellow at RTI International, an independent nonprofit research institute dedicated to improving the human condition. He is also Professor in the Departments of Epidemiology and Medicine at Boston University. His research interests in epidemiology have spanned a wide range of health problems, including cancer, cardiovascular disease, neurologic disease, birth defects, injuries, environmental exposures, and drug epidemiology, but his main career focus has been the development and teaching of the concepts and methods of epidemiologic research.