The Accreditation Council for Graduate Medical Education (ACGME) has declared medical professionalism to be a competence analogous to competence at medical practice. Medical educators accordingly seek to develop ways in which to teach and assess medical professionalism as they now teach and assess clinical medicine. The author contends that professionalism is medical morality and that while being moral in the world of medical practice can involve skill, morality differs from domain-based skills such as medicine in important respects. The norms of morality are both more exigent and more difficult to live up to than the norms of medical expertise. And any morality we learn in the course of medical education does not simply establish itself in our repertoire as a new skill, but must contend with our preexisting moral outlook. These differences have implications for the inculcation and assessment of professionalism. Professionalism can be taught, but the current model employed by medical education, cognitive engagement followed by supervised practice, will not suffice for its inculcation. Nor will objective cognitive or behavioral testing suffice for its assessment. Medical educators can seek and achieve compliance with professional norms during the formative periods of training (internship and residency). Committed observance of professional norms cannot be coerced but may emerge among trainees through their responsiveness to the lived moral life of virtuous faculty, encouraged by the tacit and explicit invitation of such faculty to imitation over time. To be valid, assessment of professionalism must be subjective, narrative, personal, undertaken during periods of stress, and obtained during routine activity (rather than on special occasions).