The behavior of parents, adult caregivers, and peers comprises the critical features of community support for the development of communication in young children with developmental disabilities. In a bio-ecological model of development, communication development is the result of the interactions of individuals with specific characteristics, in particular contexts over time. From the perspective of this model, foundational findings of intervention research to current views of communication development in children with developmental disabilities are summarized. The contributions of individual child characteristics to child-caregiver interactions that support language development are illustrated based on research with children who have autism, Williams syndrome, Down syndrome, and children who use augmentative communication systems. Parent-child interaction and the quality and quantity of parent talk are discussed as factors in children's language development. The effects of young children's delayed language on their interactions with peers, the contributions of peers to children's language learning and use, and the critical features of classroom settings that support child language development are reviewed. MRDD Research Reviews 7:143-150, 2001.