Although there is consensus that ADHD children have serious social problems, there is little understanding of the mechanisms underlying or accompanying such problems. To examine the possibility of atypical or faulty social reasoning, we presented ADHD and normal boys with a social perception task that entailed evaluating the behaviors of unknown peers. ADHD "judges" participated under both methylphenidate and placebo conditions, and on each occasion they evaluated an unfamiliar ADHD "target" in each medication state. In contrast to placebo, methylphenidate appeared to dampen overall response rates in ADHD judges, but there was no effect on sensitivity to medication-related differences. Regardless of their own medication state, ADHD judges identified more undesirable behaviors in peers on placebo than in those taking methylphenidate. Judges with the most serious behavior problems tended to identify the greatest number of negative behaviors in peers, especially when both judge and target were unmedicated. There were no effects of target medication status on detections of positive behaviors and few differences in detection patterns of ADHD versus normal judges. Discussion focused on the need to distinguish general regulatory from specific social-cognitive processes.