Daniel E. Singer, MD, is Professor of Medicine at Harvard Medical School, Professor in the Department of Epidemiology at the Harvard School of Public Health, and Associate Chief for Research in the Division of General Internal Medicine at Massachusetts General Hospital. Dr. Singer has applied epidemiologic methods, including both observational studies and randomized trials, to common medical conditions. He is most widely recognized for his contributions to stroke prevention in atrial fibrillation. He has, as well, worked with Dr. Nancy Rigotti for more than 25 years on studies of smoking cessation. Dr. Singer’s research work has been recognized by several awards, including the Society of General Internal Medicine’s highest research award, the John Eisenberg Award, and his training of mentees by Harvard Medical School’s William Silen Award for lifetime achievements in mentoring.