Throughout history there have always been confusion and even contradictions concerning professionalism. An occupation can be considered a profession in one country and not another, and in one historical period and not another. One contribution to this confusion is the explanation of the social system by Talcott Parsons and others, which has framed too narrowly and too cognitively the terms of the discussion of professions. Missing from this explanation were two of the most active cultural ingredients in the mixture of motives for professionalization. First, professionalism gave priority to the autonomous individual agent exhibiting a degree of creativity and personal independence of mind in social activity. Second, professionalism allowed a person to prepare in a context where the substance or content of a field could make an intrinsic difference in creating a professional identity, e.g., in medicine, disease composed such a content. To help answer the question "Who is a professional?", professional historians should give more attention to the cultural ambiguities internal to their own subject. (RM)