This report examined the effect of methylphenidate on social communication and self-regulation in children with pervasive developmental disorders and hyperactivity in a secondary analysis of RUPP Autism Network data. Participants were 33 children (29 boys) between the ages of 5 and 13 years who participated in a four-week crossover trial of placebo and increasing doses of methylphenidate given in random order each for one week. Observational measures of certain aspects of children's social communication, self-regulation, and affective behavior were obtained each week. A significant positive effect of methylphenidate was seen on children's use of joint attention initiations, response to bids for joint attention, self-regulation, and regulated affective state. The results go beyond the recent literature and suggest that methylphenidate may have positive effects on social behaviors in children with PDD and hyperactivity.