Delays and deficits in language development are among the cardinal features of autism, and a substantial minority of individuals with autism never aquire functional speech. It is not known how much spoken language these non-verbal individuals actually understand. A key problem is that it is difficult to assess a nonverbal child's receptive language skills using standardized testing measures. The primary goal of the present study is to develop novel methods for testing language comprehension of children with autism, and to use these methods to test developmental changes in language in preschool-aged children. This project will investigate the use of eye movements as a sensitive measure of language processing in young children with autism. Tracking eye movements is routinely used to measure comprehension in normally developing preverbal infants. The feasibility of using this method with preschool-aged autistic children will be evaluated using a series of experimental tasks to test the children's comprehension of various language structures (nouns, verbs, relational language, noun phrases, verb phrases, and word order). Performance on eye-tracking measures will be compared to standardized test scores to test the hypothesis that children with autism will show significantly greater comprehension of spoken language when tested using eye-movement measures than when evaluated on standard tests. Children will be invited to return six months after their initial testing to repeat the experiments and test the sensitivity of eye-tracking measures to developmental changes in language knowledge. This research will pave the way for developing new approaches to evaluating the comprehension skills of children with autism that can be used in research and applied clinical settings.