The purpose of the current study was to test the ability of adolescents and young adults with childhood ADHD to reliably self-report delinquency history. Data were examined from the Pittsburgh ADHD Longitudinal Study (PALS), a follow-up study of children diagnosed with ADHD between 1987 and 1996. Self-report of lifetime delinquency history was compared to concurrent parent-report and to self-report 1 year later. Participants included 313 male probands and 209 demographically similar comparison individuals without ADHD. Results indicated that adolescents and young adults with childhood ADHD were more likely than comparison participants to fail to report delinquent acts reported by a parent and to recant acts they endorsed 1 year earlier. This trend was most apparent for acts of mild to moderate severity. After controlling for several covariates, current ADHD symptom severity and parent-report of the participant's tendency to lie predicted reporting fewer delinquent acts than one's parent. Current ADHD symptom severity also predicted more recanting of previously endorsed acts. Based on these findings, several recommendations are made for the assessment of delinquency history in adolescents and young adults with childhood ADHD.