In a videotaped free-play session with a parent, autistic children were compared with mental-age matched Developmental Language Delay (DLD) children and with normally developing (ND) 2-year-olds in the use of communicative acts by parent and child. Groups were matched for language level. Autistic children had more incidents of no responses, produced less affirming, turn-taking vocalization, and gesture, and were less likely to initiate communication than other children. Parent groups differed only in a greater amount of initiating and use of imperatives by parents of autistic children. Few relations between parent behaviors and child behaviors were found. Nonresponses by all children were concentrated subsequent to parent imperatives and questions, but no group differences were found in the distribution of nonresponses to various parent communicative acts. Results are interpreted to support the hypothesis that autistic children's language can serve a number of useful functions but that their pattern of language functions differs from that of nonautistic language-impaired children and much younger normal children of similar language level.