Frank E. Speizer received his medical degree from Stanford University and did his internal medicine residency at Boston City Hospital and Stanford-Palo Alto Hospital. His epidemiologic career was shaped by fellowships at the Harvard School of Public Health (HSPH) and the British Medical Research Council Statistical Research Unit. Returning to the Channing Laboratory at Harvard Medical School (HMS), he started a research program in the epidemiology of chronic diseases. This included two seminal prospective cohort studies, the Harvard Six Cities Study of the health effects of air pollution, and the Nurses’ Health Study of the causes of cancer, heart disease, and other diseases among women. He initiated a training program in the clinical epidemiology of lung and heart disease that produced many today’s leaders in the field. He has been active in the translation of scientific evidence into policy, and is a member of the Institute of Medicine of the National Academy of Sciences. He is currently the Edward H. Kass Distinguished Professor of Medicine at HMS and Professor of Environmental Science at HSPH.