Vocational education teachers in Quebec differ from their colleagues in other teaching sectors (Descheneaux, Monette et Tardif, 2012) in that they have practiced a profession for several years before teaching it. In addition, they enter onto their teaching careers without any initial pedagogical training. Their relationship to knowledge (Charlot, 1997) is often based on a certain tension toward the educational institution and what it represents (Beaucher, 2014), as well as on the value accorded to technical knowledge, whether concrete or related to the practice of their trade. Simultaneously involved in a tridimensional process of transition between the trade and the teaching, of professional integration into teaching, and of academic integration into the university, they rely first on what is most familiar to them: their trade and their experience as students. This text presents ethical questions raised by the intertwining of four poles of identity (professional, teacher, former student and student) occupied simultaneously by the participants.