This article studies the meaning of professionalism in current attempts to professionalise teachers by means of education. The point of departure for our analysis is a small-scale survey among Swedish and German student teachers on their perception of the meaning of professionalism with regard to teachers' work. The article presents two contrasting ideal types of professionalism identified in this data: the concept of "science-based professionalism" is characterised by an ambition to develop theories that can be translated into more or less-direct prescriptions for the efficient exercise of the profession; the concept of "pedagogic professionalism," in contrast, originates in basic mistrust of this ambition concerning teachers' work and instead aims to develop a thorough understanding of the paradoxes and antinomies of education. The article outlines the theoretical foundations of these ideal types and shows how they can shed light on the aims of educational research in different contexts, as well as help explain the rationale behind structural differences in the design of teacher education programmes.