The purpose of this article is to trace the development of medical professionalism in medicine from its origins to the present. Codes of professional conduct are the tangible expressions of professionalism. I use them as a window into contemporary circumstances of medical practice. The medieval guilds are my framework for examining the relationship of the medical profession in relation to society. The craft guilds of postmedieval Europe wielded considerable power. They controlled entry into a craft, training, and standards of quality. By controlling the volume of production, they controlled price. The craft guilds flourished until their monopoly powers began to hinder the forces of capitalism, which influenced the state to limit the powers of the guild. The professions are the offspring of the medieval craft guilds. Since the early 19th century, the medical profession in the United States has sought guild powers. The triangular relationship between state, capitalism, and the medical profession explains the rise of the profession during the 19th century and its decline since the mid-20th century. I argue that the codes of conduct of the profession reflect what it needs to maintain its guild powers against the forces of capitalism and the state. The Charter on Medical Professionalism calls on physicians to take into account both the individual patient's needs and those of society. I believe this important clause reflects the conflict of the profession with the state and capitalism over the aggregate costs of medical care.