Thomas Perls, M.D., M.P.H., is assistant professor of medicine, Harvard Medical School, and a geriatrician at Beth Israel Deaconess Medical Center. He is the founder and director of the New England Centenarian Study(NECS). His work has been published in the major scientific journals, described in the popular press, and highlighted in television documentaries and national news shows. Margery Hutter Silver, Ed.D., a neuropsychologist, is associate director of the NECS, a clinical instructor in psychology at the Harvard Medical School, and a staff member of the Department of Psychiatry at Beth Israel Deaconess Medical Center. She is co-editor of the Journal of Geriatric Psychiatry. John F. Lauerman, a freelance writer in Brookline, Massachusetts, is health columnist for Harvard Magazine and an award-winning contributor to national magazines. He is the author, with David Nathan, M.D., of Diabetes: Understand Your Condition, Make the Right Treatment Choices, and Cope Effectively.