Examined social information processing (SIP) in medicated and unmedicated children with ADHD and in controls. Participants were 75 children (56 boys, 19 girls) aged 6-12 years, including 41 children with ADHD and 34 controls. Children were randomized into medication conditions such that 20 children with ADHD participated after receiving placebo and 21 participated after receiving methylphenidate (MPH). Children were shown scenarios depicting peer interactions and asked to interpret each scenario and to generate possible responses to the scenario. Results showed that children with ADHD who received MPH generated more hostile responses to provocation than controls, but children with ADHD on placebo did not. Results also showed that children with ADHD regardless of medication generated more hostile responses to provocation than to peer entry, whereas controls did not. Findings suggest that children with ADHD generate more aggressive responses to provocation than controls and that this may be exacerbated by administration of MPH. Limitations and future directions are discussed.