Using a social-ecological framework, this case study examined communicative competence through classroom interactions involving Aaron, a preschool-age child with autism who utilized an augmentative and alternative communication device (AAC). In addition to Aaron, participants included Aaron's father, the school director, classroom teachers, a paraprofessional, and 17 of Aaron's preschool classmates. The present analyses relied on ethnographic data collected by Russell and Valentino (2013)—specifically, five observations of classroom activities involving Aaron, one of which was video recorded, and six semistructured interviews of adult participants. Our extended analyses included a categorical analysis focused on communicative offers to and from Aaron as recorded in observational field notes and a new situated discourse analysis of the video-recorded small group activity. Together results revealed three key components of communicative competence: (a) presumed competence, (b) flexible multimodality, and (c) synchronized repetition. Implications focus on how to conceptualize and support communicative competence for children who use AAC from a social-ecological framework.