This paper examines the history of Finnish didactics and the professionalization of teacher education. In Finland, didactics is an emerging academic discipline--the science of teaching or educational science for teacher education--and includes both the subject and contextual knowledge of teaching. At the same time, the context of teaching and learning, the school as a socio-historical institution, is of little interest. Education discourse in Finland since the 1860s is analyzed, as well as the recent development of department-level curricula for classroom teacher education at six Finnish universities in the 1980s and 1990s. Teacher professionalism in relation to the interests and professionalism of teacher educators is explored, as well as the theory of "social closure," in which professional status results from a group seeking to achieve monopoly in its field of activity and exclude other competing groups from the market. The results of the analysis suggests that while pursuit of a coherent picture of school teaching and learning requires involvement with other disciplines, the professionalism drift of teacher educators toward recognition of didactics as a distinct field works against this involvement. While pursuing justification of their existence as an academic field, teacher educators are excluding competing disciplines and constructing a social closure and a closed market ruled by their monopoly in the field. (Contains 72 references.) (ND)