<p>This paper addresses the question of how the professionalization of teacher educators can be theoretically described and empirically researched. We elaborate on this question using group discussions with teacher educators about their case-based teaching. The study is grounded in the Praxeological Sociology of Knowledge, both theoretically and methodologically. We employ this approach to develop professional-theoretical propositions regarding the professionalization of teacher educators and to analyze our data because we use the Documentary Method to explore professionalization processes empirically. The question of (tensioned) relationships between various habitus and norms and their collective perception and management turns out to be central for professionalization. Finally, through the interplay of professional theory and empirical research, we suggest the concept of a&#xa0;documentary higher education research.</p>