Neuroimaging research is beginning to characterize several important ways in which the brains of persons with an autism spectrum disorder (ASD) develop and function differently. ASD is a heterogeneous disorder, with individual differences in severity of symptoms, various aspects of behavior and cognitive functioning. This project will use magnetic resonance imaging (MRI) to study the brain anatomy and function. These measures will be correlated with differences in symptomatology and behavior in order to enhance the understanding of the brain-bases of the ASDs. This research is guided by the belief that understanding the fundamental mechanisms that cause ASDs will allow for the development of better interventions and treatments.