The analysis proposed in this article is situated at the micro-level of inter-individual formative encounters between a teacher-mentor and a beginning teacher, participants in program for initial teacher education. Findings of this analysis indicate that whilst engaged in collaborative work on the object of their activity -building common professional knowledge as part of the professional identity formation process - the participants come to shape the space of their joint exploration of the tools available and engage in producing their professional culture, by generating between them a space of communication where tools are to be born, transformed, melted into practice, questioned and then transformed again. In return, the conceptual actions performed function as maps for participants' expanding professional agencies. This work has been supported by CNCSIS -UEFISCSU, project number PN II-RU 21/2010. (C) 2012 Published by Elsevier Ltd. Selection and/or peer-review under responsibility of The Association of Science, Education and Technology