We tested the construct validity of scores from the Attention Deficit Hyperactivity Disorder Behaviour-Rating Scale (ADHD-BRS) within South African early childhood classrooms in three of the eleven official languages, English, Afrikaans, and isiXhosa. In-service teachers (n = 109) from 112 schools in the Western Cape Province completed the ADHD-BRS for 1 771 Grade One children (female = 50%; median age = 7.39 years). Rasch analysis and Confirmatory factor analysis (CFA) results indicated evidence for the validity of the ADHD-BRS scores. There was evidence that the language of learning and teaching (LoLT) groups differed enough to require separate analysis. Regardless of language or sex, higher scores on inattention predicted lower reading and numeracy scores across groups.