Objective: To determine if adults with ADHD differed from children with ADHD, in assessing their performance on the Conners Continuous Performance Test (CPT). Method: ADHD-diagnosed adults (n = 13) and adults without ADHD (n = 17) were tested twice on the CPT and then completed self-evaluation and attribution surveys. Results: Nonmedicated ADHD-diagnosed adults performed significantly more poorly than controls; when medicated, they performed as well as controls and significantly better than when they were unmedicated. AD/HD adults evaluated their performance accurately, whether medicated or not. They also attributed their performance to medication significantly more than to ability or task difficulty. Conclusion: Unlike children, ADHD-diagnosed adults attributed their performance to medication rather than ability or task. It remains to be seen whether this difference is associated with lower self-esteem than non-ADHD adults or if the same outcome would occur in children with ADHD if they were also tested under naturalistic conditions. (Contains 1 table.)