Evaluated discriminant validity and clinical utility of selected subscales of the Devereux Scales of Mental Disorders (DSMD; Naglieri, LeBuffe, & Pfeiffer, 1994) and the Child Behavior Checklist (CBCL; Achenbach, 1991a) in 228 children referred to a clinic for the evaluation and treatment of attention deficit hyperactivity disorder (ADHD). The DSMD is a multiaxial behavior rating scale that measures symptomatology for a broad range of child psychopathology as described in the Diagnostic and Statistical Manual of Mental Disorders (3rd ed., rev. [DSM-R-III] and 4th ed. [DSM-IV]; American Psychiatric Association, 1987, 1994). Discriminant function analyses as well as sensitivity, specificity, and predictive power analyses were computed to evaluate the discriminant validity and clinical utility of selected DSMD and CBCL subscales for assessing ADHD, oppositional defiant disorder (ODD), and anxiety disorders. Results indicated that the DSMD compared very favorably with the CBCL in the ability to discriminate between children with ADHD and those without ADHD and between children with comorbid ODD and anxiety disorders and children who did not meet criteria for these disorders. The DSMD Attention subscale may be somewhat better at ruling in ADHD combined subtype (ADHD-C) and ADHD inattentive subtype (ADHD-I) than the CBCL Attention Problems subscale, but the CBCL Attention Problems subscale may have slightly better utility than the DSMD Attention subscale in ruling out these subtypes. Both the CBCL and DSMD were more useful for ruling out than for ruling in ODD and anxiety disorders.