Objective: Clinical utility of the Behavior Rating Inventory of Executive Function, Second Edition (BRIEF2) was examined in 1,381 clinically referred youth (62.5% male, 5 to 18 years) with and without ADHD symptoms. Method: Participants included children with restricted inattentive symptoms (IA only), restricted hyperactivity/impulsivity symptoms (HI only), symptoms in both domains (Combined), and non-ADHD clinical comparison. Results: Greater hyperactivity (Combined, HI only) was associated with higher Behavior Regulation (BRI) and Emotion Regulation (ERI) scores, whereas greater inattentiveness (IA only, Combined) was associated with higher Cognitive Regulation scores. Effect sizes were largest for Inhibit, Working Memory, and Organization of Materials scales; these scales discriminated children with and without ADHD symptoms and restricted inattentive and hyperactive presentations. Conclusion: The BRIEF2 distinguishes associated features of ADHD and the day-to-day executive impact. Sensitivity was consistently poorer than specificity. The referred nature of the sample and examination of restricted presentations suggest additional work is needed to examine whether ERI and BRI are dissociable.