The purpose of the study was to test the applicability of the Child Behaviour Checklist for assessing behaviour problems and competencies in Norwegian children and adolescents. Information was obtained by mailing checklists to parents of random sampled children and adolescents in a mixed rural/semirural area and the urban Oslo area. High-scoring children and random samples of normal-scoring children in two different age groups were clinically assessed in the second part of the study. The results support the predictive validity of the CBCL as judged by its ability to distinguish between children with psychiatric disorders and psychiatrically non-disordered children. Differences pertaining to sex, age, SES, and degree of urbanisation confirm findings of earlier studies across cultures.