Purpose: Repeated measures of communica- tive intention, vocabulary, and grammar were collected from a child with autism during the course of commu- nity-based treatment. Method: Data were collected for 14 months using language samples and the MacArthur Communicative Development Inventory (Fenson et al., 1993). Results: During every session, the child's abilities in communicative intention, vocabulary, and grammar were lower than expected for his age. Nevertheless, the child increased his abilities in all 3 areas across time. His growth in the social engagement domain for communica- tive intents rather than in the behavior regulation domain was positively related to his development of expressive language. Conclusion: These findings are consistent with other studies that have examined similarly aged children with autism who also showed high and steady advances in their development of language during the course of com- munity-based treatment. For clinical purposes, repeated measures of these 3 skill areas helped confirm the high functioning language status and positive growth trajectory of the child relative to other children with autism.