Individuals with autism spectrum disorder (ASD) demonstrate deficits in social behavior which may hinder them from engaging in social interactions. Results of descriptive analyses suggest that children who engage in prosocial behaviors, such as sharing, likely receive social positive reinforcement from peers in the form of attention. However, functional relations between prosocial behaviors, such as sharing, and their maintaining consequences have yet to be identified. Thus, the purpose of this study was to extend previous research by evaluating the naturally maintaining contingencies associated with sharing in three preschool-aged children with ASD. Functional analyses have traditionally been used to identify the function of maladaptive behavior; however, we extended the same methodological approach to identify functional relations of sharing. Results suggest that sharing was maintained by attention for two participants and was multiply-maintained by both attention and access to tangibles for one participant. These findings indicate that the functional analysis methodology is appropriate to understanding prosocial behaviors. In addition, results advance our understanding of prosocial behavior and may better inform methods of how to functionally teach sharing to individuals with ASD.