The aim of this study was to examine the relationships between intelligence, ratings of behavior, and continuous performance test scores for a sample of 117 children aged 6-16 years who were referred to a specialty clinic. The sample was comprised of children who had a primary (45%) or secondary (36%) diagnosis of ADHD. All children were given the Wechsler Intelligence Scale for Children Third Edition (WISC-III), Cognitive Assessment System (CAS), Conners' Continuous Performance Test (CPT), and Conners' Parent and Teacher Rating Scales--Revised, Long Form. Correlations between Conners' Behavior Rating Scale and Conners' Continuous Performance Test were uniformly low and non-significant (the highest correlation was .17). Correlations between the WISC-III and Conners' Parent Rating Scale were all non-significant, but Teacher Ratings showed significant correlations between most of the WISC-III factors and the Cognitive Problems/Inattention scores. Few significant correlations were found between CPT with the WISC-III and CAS. These results suggest that practitioners should expect to find a lack of consistency between the scores provided by these measures and should be conservative of their use in clinical settings.