Compared the effectiveness of discriminating attention deficit/hyperactivity disorder (ADHD) subtypes using the Parent Rating Scale (PRS) and Teacher Rating Scale (TRS) of the Behavior Assessment System for Children (BASC) and the Parent Report Form and Teacher Report Form (TRF) of the Achenbach Child Behavior Checklist (CBCL). To determine the extent to which these scales measured similar behaviors, Pearson Product-Moment Correlations were computed for the parent scales (PRS and CBCL) and for the teacher scales (TRS and TRF). Results indicated that correlations were significant for a number of scales. Discriminant analysis does not suggest a strong advantage of either measure in differentiating children with ADHD from those who do not meet criteria for ADHD, except for the BASC TRS which has better predictive ability for children who do not meet ADHD criteria. For subtypes of ADHD, and specifically the ADHD: Predominantly Inattentive subtype, however, results would favor the use of the BASC PRS and TRS.