Objective: Poor parent and teacher awareness for attention-deficit/hyperactivity disorder (ADHD) and the scepticism of many clinicians on the prevalence of the disorder, make Italy an interesting environment in which to verify neuropsychological constructs generated in a predominantly Northern American cultural contest. The aim of the study was to verify, by factor confirmatory analysis, the empirical validity of the DSM constructs underlying the diagnostic criteria for developmental disruptive behaviour disorders in Italian school-age children. Methods: Scores for DSM-IV inattention and hyperactivity/impulsivity, for oppositional defiant disorder (ODD) and for conduct disorder (CD) symptoms in 6-12 years old Italian children were analysed from 1575 parent and 1085 teacher forms of the disruptive behaviour disorders questionnaires collected in four different Italian regions. Results: Reliability indicates high internal consistencies for both parent and teacher rating of inattention, hyperactivity/impulsivity, and oppositionality, but not for conduct problems. In accordance with the literature, a relatively low inter-rater convergent and discriminant validity correlation was observed comparing measures obtained by between parents and teachers. Confirmatory factor analysis of both parent and teacher data showed a better fit for a four-factor model, indicating a factor structure in accordance with the DSM-IV taxonomy. When completed by parents and teachers of clinically assessed ADHD, dyslexic or normal children, the disruptive behavioural disorder questionnaires showed a significant predictive diagnostic value. Conclusion: Although an informant variance higher that dimensional (trait) variance was observed, the study provides support for DSM-IV taxonomy for developmental disruptive disorders, showing construct validity of ADHD. ODD and CD could also be distinguished from each other. © 2005 Elsevier SAS. All rights reserved.