Functional connectivity in the brain refers to the synchronization of neuronal assemblies for the purpose of transferring information within and between these assemblies. Long-range cortical functional connectivity refers to connectivity between distant cortical areas, and is often reduced in autism spectrum disorders (ASD). The nature of local cortical functional connectivity (connectivity within a neuronal assembly) has remained elusive in studies of ASD, but it has been generally believed that local functional connectivity is increased in ASD. We used magnetoencephalography (MEG), a technique that reveals cortical activity with high spatial and temporal resolution, to measure functional connectivity both locally and between distant cortical regions while ASD and typical individuals viewed houses and faces. Contrary to the prevailing hypothesis, we showed that local functional connectivity was reduced, not increased, in ASD. Furthermore, the strength of local functional connectivity correlated with ASD severity, and statistical classification using local and long-range functional connectivity data identified ASD diagnosis with 90% accuracy. Finally, we found that the strengths of local and long-range functional connectivity were correlated in both ASD and typical individuals. These results suggest that failure to adequately synchronize neuronal assemblies both within and across cortical regions is characteristic of ASD. Here we propose to extend this work in several ways. First, we propose to study local functional connectivity in ASD in multiple cortical areas during performance of both visual and auditory paradigms by younger subjects. Second, we propose to examine carefully the links between local and long-range functional connectivity, to determine how the two patterns interact. Lastly, we intend to identify a set of measures of local and/or long-range functional connectivity that correlate highly with diagnosis and severity of ASD, for future development into early biomarkers of ASD.