This study investigates the practice of achieving common understanding in aided Augmentative and Alternative Communication (AAC). The aims are to explore whether communicative contributions can be described as turns, as defined in conversation analytic terms, and how then the contributions to the interaction can be designed. The principles and practices of Conversation Analysis (CA) were used to record, transcribe and analyse conversations between a non-speaking boy with cerebral palsy with, on different occasions, his mother, his assistant and his friend. The boy augments his communication with aided AAC, bliss symbolics. The analysis indicates that the participants can collaborately create and orient to units in interaction equivalent to turns in interaction although they differ dramatically from ordinary turns-at-talk. In order to capture the nature of the described units, the category turn-at-action is suggested. The analyses demonstrate that the boy’s turn-at-actions are oriented to as a co-constructed and thus interactionally achieved unit: the boy points at a bliss symbol which is given voice by the speaking co-participant. In and through the relevant made voicing of the turn-at-action, a turn constructional unit (TCU) emerges, and the turn-at-action is designed and oriented to as a TCU-based unit. The analysis will also show that turns can be designed as non TCU-based units. These findings may have implications for CA theory as well as for clinical intervention.