Bruce A. Leff, M.D., is professor of medicine at the Johns Hopkins University School of Medicine. He holds a joint appointment in the Department of Health Policy and Management at the Johns Hopkins University Bloomberg School of Public Health. Dr. Leff is director of the Center on Aging and Health (COAH) Program in Geriatric Health Services Research and codirector of the Elder House Call Program in the Division of Geriatric Medicine at the Johns Hopkins University School of Medicine. His principal areas of research relate to home care and the development, evaluation, and dissemination of novel models of care for older adults. Dr. Leff has served on multiple technical expert panels for the Centers for Medicare & Medicaid Services on issues related to geriatrics and home health care.