Performance-based measures and ratings of executive functions were examined in a sample of adolescents with attention deficit/hyperactivity disorder (ADHD) and comparison controls. Performance-based measures of executive function included inhibition, working memory, set shifting, and planning, and ratings of these same executive functions were completed by parents and teachers. Adolescents with ADHD demonstrated lower executive function performance than controls and displayed elevated ratings on the executive function ratings by parents and teachers. Significant associations were obtained between the performance-based measures and the parent and teacher ratings, but each measure was not uniquely associated with its respective scale on the rating scales. When performance-based measures and ratings were examined as predictors of ADHD status, the parent and teacher ratings entered as significant predictors of ADHD status. Further commonality analyses indicated that performance-based measures accounted for little unique variance in predicting ADHD status and also displayed little overlap with the behavioral ratings. These findings highlight the diagnostic utility of behavioral ratings of executive function in predicting ADHD status; however, behavioral ratings should not be assumed to be a proxy for performance on measures of executive function in clinical practice.