The current study examined the psychometric properties and sensitivity to brain dysfunction of a popular test of abstraction and problem solving ability, the Children's Category Test Level 2 (CCT-2; Boll, 1993). Participants were 113 children with various forms of structural brain damage (n?82) or with Attention-Deficit/Hyperactivity Disorder (n?31). Results indicated that while there is some support for the validity of the CCT-2, the test is not particularly sensitive to brain dysfunction. The composite T-score, subtest scores and factor scores did not distinguish children with ADHD from those with structural brain damage and the T-scores of both groups were within the normal range. These results illustrate the importance of validating measures of neurocognitive function with clinical populations as even tests with otherwise excellent psychometric properties may not be sensitive to brain dysfunction. It is recommended that the CCT-2 not be used to draw conclusions regarding the impact of brain damage on abstraction and problem solving abilities.