This research draws on the experiences of two new teacher educators to sketch the beginning of a theory accounting for a process of transition from classroom teacher to teacher educator. As these two educators negotiated the transition from the world of classroom teaching to that of the university-based teacher educator, attention was focused on the knowledge bases they employed in their decision making, the institutional/contextual challenges and supports they experienced, and the extent to which their professional identities as teacher educators drew from their time spent in school classrooms. The result is a set of four broad categories that establish a framework for thinking about the move from teacher to teacher educator: shifting role identification, institutional and cultural context, frames of understanding and knowledge, and the practice arena. Twelve additional sub-categories are nested within these four "problematics of practice." Together, these categories represent a starting point for further conversations about how teacher educators develop their identities and professional expertise. (Contains 25 references.) (SM)