In schools for adolescents with co-enrollement, students with hearing impairment are instructed together with normal hearing students. To help the students with hearing disability, a teaching assistant is employed. This chapter explores the interactional organization of such a classroom during a phase where one of the hearing impaired students solicits the assistant’s help. The analysis reveals how the student handles two conflicting constraints. On the one hand, he needs to mobilize the assistant’s attention to solve his understanding problem, on the other hand this action needs to be launched in such a way that the ongoing plenary teaching activity can continue simultaneously. Given the difficulties in achieving intersubjectivity under these conditions, the authors recommend that teaching assistants employed to help with integration of hearing impaired students should have sign language competence.