Prognosis for children with autism spectrum disorder (ASD) receiving intensive early intervention has improved substantially. A minority of these children appear to reach what may be called "optimal outcome," in which cognitive and adaptive functioning are within normal limits, and they no longer meet criteria for any ASD. While these optimal outcome children regain many normal language functions, preliminary studies show that some language impairments persist. These preliminary results raise the question: what are the underlying neural mechanisms of the striking improvement of cognitive processes in these optimal outcome children? Functional magnetic resonance imaging (fMRI) will be used during tasks of syntax and face processing to address this question, and exploratory analysis of selected structural variables will be examined to see if the most successful intervention appears to operate on a structurally normal brain.