This chapter examines the accumulated evidence for the relation between neuropsychology and conduct problems in children and adolescents. It provides evidence for a link between neuropsychological health and conduct disorder. One of the most robust correlates of severe conduct problems is impaired verbal ability. Verbal deficits have been found in conduct-disordered children, serious adolescent delinquents and adult criminals. Evidence of the relation between executive deficits and conduct problems has been found among incarcerated subjects, among non-conduct-disordered subjects in laboratory situations, and among general-population samples. The cumulative effect of the neuropsychological deficits and the consequent social and academic failures results in a pattern of undercontrolled, explosive behaviour which persists across the life course. The relations between poor neuropsychological functioning and conduct problems were robust across diverse samples, particularly strong for severely anti-social subgroups, and survived conservative controls for possible third variables.