Objective: Current theories hypothesize that deficits in executive functioning (EF) are responsible for the symptoms of ADHD and that specific patterns of EF deficits may be associated with different subtypes of ADHD. The present study evaluates the validity and clinical usefulness of the Behavior Rating Inventory of Executive Function, a behavior rating scale designed to assess dimensions of EF. Method: Participants include 70 boys and girls between the ages of 5 and 13 referred to a university-based clinic for assessment of ADHD. Results: Results indicate low interrater reliability but acceptable convergent validity. Conclusion: Parent report on the Behavior Regulation scale differentiates the ADHD—Combined Type group from the ADHD—Inattentive Type and non-ADHD groups, and the Metacognitive Index differentiates both ADHD subtypes from the non-ADHD group, thus supporting the clinical utility of this measure in a clinic-referred sample. (J. of Att. Dis. 2007; 10(4) 381-389)