In this paper, relying on the sociocultural framework of learning, we report on the results of an ethnographically-grounded investigation of agency work among nine pre-service teachers: The main objective is to determine how agency emerges and is constructed in situated discourse practices within the context of a teacher education program embedded in the collective inquiry approach. Our study identifies the forms of agency that emerged in the collective discussions of the classroom community, evidencing pre-service teachers' transformative agency, relational agency and epistemic agency. This study also shows that the negotiation and framing of agency, and acting as accountable authors, involves changes in teacher-student positions, such as crossing and transforming traditional expert-novice boundaries, as well as recognizing and crediting this crossing of boundaries. The methods and conditions for supporting students' agency work in teacher education are discussed.