This paper examines the sorts of interactional competencies and institutional demands required from students as they engage in complex forms of participation combining work and training purposes. It focuses on a series of empirical cases, recorded through video data and analyzed from a conversation analytic perspective, in which mentors make the decision to intervene during work sessions moderated by students. Such interventions do not interrupt the student’s activity and lead to the emergence of two distinct but not impermeable interactional spaces. This complex participation framework, known as “schisming,” contributes to overcoming practical issues within multiparty settings. Our study shows how schisming constitutes a particular sequential phenomenon where participants reorganize the interaction and co-construct a social and cognitive interactional space, thus enabling a shared understanding of the specific training context. Empirical data from the practical training of medical radiographers are used to illustrate how schisming may contribute to learning in the conditions of guided practice.