The observational study examined the sign language and communication abilities of 10 nonspeaking, autistic and autisticlike children (6 to 14 years old) involved in simultaneous communication training. Video data were collected as each child interacted with his/her therapist and with an unfamiliar adult. Analyses of the children's and adults' language use were based upon M. Halliday's sociolinguistic model and upon case grammar theory. A large proportion of child utterances were imitative or ritualistic in nature. Variability between children was apparent in terms of linguistic spontaneity and overall productivity, though each child demonstrated the ability to employ signs in the service of social interactional goals. Nine of the ten children used signs in a combinatorial fashion in order to express case (or semantic) relations. Findings have implications for the design of language training procedures for autistic and other linguistically handicapped children. (Author/SB)