Objective: Behavioral rating scales are common instruments used in evaluations of ADHD and executive function. It is important to explore how different diagnostic groups perform on these measures, as this information can be used to provide criterion-related validity evidence for the measures. Method: Data from 92 children and adolescents were used to examine differences among participants in a No Diagnosis group, ADHD group, and Other Clinical group in terms of parent and teacher ratings on the Behavior Rating Inventory of Executive Function (BRIEF) and Conners' Rating Scales Revised--Short Form. Results: Participants in the ADHD and Other Clinical groups generally received similar scores on the scales, and both groups were generally rated higher in ADHD characteristics and executive dysfunction than were participants in the No Diagnosis group. Conclusion: Although the measures were successful at distinguishing clinical from nonclinical participants, their ability to distinguish among different clinical groups deserves further investigation. (Contains 5 tables.)