Background: This study investigated whether problem behaviour in 5- to 6-year-old children is related to parental education and occupation. It also analysed the contribution of correlating factors to explain this association. Method: The Child Behaviour Checklist was administered to a large community sample of 1317 children who were in the 1st year of normal primary school in the Netherlands. Outcome measures were total problem score, and externalising and internalising scale scores. Results: Results of the logistic regression analyses indicated that higher rates of reported behaviour problems were significantly associated with low parental education and occupation. These associations were mediated by low maternal age at delivery and single-parent families. The number of children in a family and physical illness of the parents did not contribute to these associations. Conclusions: Parental education and occupation have a large impact on the mental health of young children. Psychosocial and biological factors are possible explanations for this phenomenon.