Functional magnetic resonance imaging (fMRI) uses the relationship between blood flow in the brain and neuronal activity to identify areas of brain activity associated with specific cognitive functions; diffusion tensor imaging (DTI) uses the movement of water molecules in the different tissues in the brain to determine the structural pathways in the brain. This project will combine these neuroimaging techniques with behavioral tasks which measure attention and executive function to the study two of the core deficits in children with ASD and to compare them to typically developing children. Functional MRI will be used to identify areas of the brain active with frontal lobe functions and DTI will be used to identify the connections between brain regions. Dr. Taylor's study will investigate the neuroanatomy and brain function of children with ASD to determine if nerve pathways between brain regions have weaker connections, and if brain activity during specific cognitive tasks is less focused than non-affected children. The results will determine if the children with ASD have atypical activation (with fMRI) with these tasks, or if the poor performance is due to less robust interconnections (with DTI) among the networks implicated. Significance: By identifying behavioral and neuroimaging patterns characteristic of the core deficits in ASD, earlier diagnosis and intervention could be attained. Furthermore, an improved understanding of the neurocognitive underpinnings of ASD will allow for the development of focused treatment strategies and accurate neuroimaging monitoring of their efficacy.