This study evaluated the appropriateness of scoring the Behavior Rating Inventory of Executive Function--Preschool (BRIEF-P) using age-equivalent scores generated from multiple measures of cognition and language among school-age children with Down syndrome (DS). Subscale T scores for 95 children with DS were contrasted using standard scoring on the Behavior Rating Inventory of Executive Function--Second edition (BRIEF-2; based on chronological age) to alternate scoring using the BRIEF-P (based on age equivalent) for patterns of subscale intercorrelations, differences in mean scores, and agreement on findings from clinical cut-off scores. Results with children with DS suggested using (1) the BRIEF-P for children ages 2-5 years old, (2) the BRIEF-2 with chronological-age scoring or the BRIEF-P with age equivalent scoring (with some caveats) for research on children ages 5-10 years old, and (3) the BRIEF-2 for children ages 11 and older.