In the age-group 4–5, the internal consistency of Hyperactivity-Inattention, Prosocial behaviour, Total difficulties and Externalising was satisfactory to good (Cronbach’s alpha coefficients .71–.80). Internal consistency of Emotional symptoms and Internalising was moderate (Cronbach’s alpha coefficients .66 and .67). Internal consistency of Conduct problems and Peer problems was insufficient (Cronbach’s alpha coefficients .42 and .48 respectively).