The social cognitive deficiencies of children diagnosed with autism spectrum disorders (ASDs) are well documented. However, the mechanisms underlying these deficiencies are unclear. Therefore, we examined the social information processing (SIP) patterns and social behaviors of 25 preschool children with ASDs in comparison to a matched group of 25 typically developing children. We found children with ASDs to be less likely than typically developing children to efficiently encode social information, to positively construct and evaluate competent responses, and to exhibit prosocial behaviors. They were also more likely than typically developing children to attribute hostile intentions to others in benign social situations, to construct and evaluate more positively aggressive responses, to construct more avoidant responses, and to display more externalizing behaviors. Interestingly, counterintuitive patterns of relationships were found within the ASD group with more competent SIP and theory of mind (ToM) patterns relating to less competent social behaviors. Finally, within the ASD group, more competent SIP patterns were found to be significantly related to higher ToM capacities.