The objective of this article is to describe the prevalence of childhood disorders and examine the factors associated with higher rates of disorder by combining the data from two large population-based samples of British children and young people aged 5-15. Just over 18,000 children were assessed in 1999 and 2004 using the Development and Well-Being Assessment, a structured interview with verbatim reports reviewed by clinicians so that information from parents, teachers and children is combined to produce national estimates of clinically recognisable disorders. The overall prevalence of childhood disorders was 9.5%. Factors which are independently associated with increased rates of childhood mental disorders ranged from characteristics of the child (age, sex, physical health problems, having poor scholastic achievement) to family characteristics (family structure, mother's psychological distress, poor family functioning) and household characteristics (tenure, type of accommodation and the working status of family). In conclusion, roughly one in 10 children have at least one ICD10 disorder, involving a significant level of distress or social impairment. Associations with child, family and household characteristics have implications for treatment strategies. (Contains 3 tables.)