The present study examines how interactional competences of autistic children are co-constructed by different co-participants. In our video-ethnographic case study we follow Andy, a boy diagnosed with Asperger syndrome, across interactions with different partners and different activities in inclusive educational settings. The comparative analysis of Andy‘s participation in a group activity with his peers and in classroom discussion demonstrates that competence ascriptions and actual competence displays vary widely. While the peers’ trust in Andy’s competence enabled him to meet their communicative expectations, both the teacher's and the teaching assistant’s behavior exhibited their limited trust in Andy’s competence to make meaningful contributions and resulted in self-degradation and embodied disengagement. We then present our findings with regard to how trust in a group’s members’ interactional competencies, competence ascriptions and competence displays mutually inform each other.