Purpose: Autism spectrum disorders (ASD) are characterized by early impairments in language and related social communication skills. This investigation explored whether scores on the MacArthur-Bates Communicative Development Inventory (CDI) at ages 2 and 3 years predict outcome at age 9 years in children with ASD and developmental delay (DD). Method: Sixty-two children referred for possible autism at age 2 years, and 19 children with DD, were followed to age 9 years. Vocabulary, prespeech, and gestures scores on CDIs administered at ages 2 and 3 years were used to predict follow-up IQ, language, adaptive skills, and scores on diagnostic measures. Results: CDI scores at ages 2 and 3 did not predict outcome for the DD group. For the ASD sample, CDI receptive and expressive language and late gestures at ages 2 and 3 years predicted a number of follow-up variables, although scores at age 3 years were generally more predictive than scores at age 2 years. Conclusions: The CDI yielded scores that were predictive of outcome, suggesting that this parent report measure may be a quick and informative assessment of early verbal and nonverbal skills in children with ASD.