This study examines the displayed communicative competence and agency of a non-speaking student at a compulsory school for children with severe learning disabilities. The use of two different speech-generating devices (a single-message versus a multi-message speech-generating device) and the assignment of participation role (having the role of 'student' or 'teacher') were compared in two morning meetings. The two interactional sequences 'question-answers' and 'repair actions' were chosen because they provide participants with opportunities to display communicative competence and agency. The analysis showed that the displayed communicative competence and agency of the non-speaking student differed in relation to the kind of speech-generating device and the associated participatory role. Furthermore, the displayed communicative competence and agency was a product of the close collaboration between the student and the assistant and teachers who scaffolded the process. The study shows that teachers and assistants can influence the communicative competence and agency of non-speaking students.