This chapter reviews magnetic resonance imaging (MRI) findings on developmental disabilities that arise from both modular and distributed perspectives on brain function, although the former clearly represent the majority of existing data. It focuses exclusively on autism spectrum disorders (ASD) including the diagnoses of autism, Asperger's Syndrome, and pervasive developmental disorder. Some evidence indicates that observed abnormalities in language areas may reflect different processing styles, rather than deficits per se. Visual information processing has always been a topic of great interest to ASD researchers, as individuals with ASD often show preserved and sometimes enhanced visual abilities. A large number of studies have established the role of superior temporal sulcus in various aspects of social perception. Mirror neuron system (MNS) has proven responsive to both the perception and implementation of specific body movements. The relatively high spatial resolution of MRI lends itself very well to the isolation of specific brain structures.