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Continuous Performance Test (CPT) responding was compared between 15 adults with a history (childhood/adolescent) of Conduct Disorder (CD) and 15 normal controls. Of particular interest was whether response latencies and commission errors, which have been suggested to be measures of impulsivity, would differ between the groups. The CPT procedure used included two conditions: Immediate Memory Task and Delayed Memory Task (IMT/DMT; Dougherty et aI., 1998). Both the IMT (0.5-s delay) and DMT (3.5-s delay with distracter stimuli at 0.5-s intervals) required the subject to respond if a briefly displayed number was identical to the one presented before it. Stimuli included target (identical match), catch (four of five digits matched), and novel (no match). Participants completed six 22-min testing sessions scheduled across a single day. The most significant findings were that the CD group (compared to the control group) had (a) elevated commission errors (responses to catch stimuli); (b) lower stimulus discriminability (between target and catch stimuli); and (c) shorter response latencies. These results are consistent with the few previous studies indicating that these parameters are related to impulsive behaviors.