This study evaluated the psychometric properties of a measure of Attention-Deficit/Hyperactivity Disorder (ADHD) with Native and non-Native children. Two models, corresponding to DSM-III-R and DSM-IV symptom categorizations of ADHD, were assessed by (a) determining which DSM schema of ADHD best fit the data within each culture group and (b) testing the cross-cultural equivalence of the best-fitting model. Data were taken from the Flower of Two Soils and School Options for Native Children studies, examinations of emotional health and academic achievement among Native and non-Native children. The studies included teacher, parent, and self-report ratings of symptoms among 1555 Native and 489 non-Native children in grades 2 and 4 at four different locations across North America. For the data derived from teacher and parent ratings, a 2-factor solution corresponding to the DSM-IV conceptualization of two subtypes provided the best fit. For student self-ratings, the 2-factor solution showed no improvement over a 1-factor model. The respective factor solutions were culturally invariant. Acceptable internal consistency was observed across raters and within culture groups.