edical specialization dates back at least to the time of Galen. For most of medicine’s history, however, the boundaries of medical fields have been based on factors such as patient age (pediatrics and geriatrics), ana-tomical and physiological systems (ophthalmology and gastroenter-ology), and the physician’s tool-set (radiology and surgery). Hos-pital medicine, by contrast, is defined by the location in which care is delivered. Whether such delineation is a good or bad sign for physicians, patients, hospitals, and society hinges on how we understand the interests and as-pirations of each of these groups