Background: Little is known about the factors affecting the risk of behavioural and emotional problems in young people with severe intellectual disability (ID), although such evidence as there is suggests that there may be differences between the pattern of risk factors in this group and those that operate in general population samples of the same age. Method: From a sample of 111 children with severe ID who had been initially identified from the registers of six special schools at 4-11 years, 82 were traced and reassessed on average 5 years 4 months later. The relationships between potential risk factors and behaviour problems, reported here for 11:00-17:04 year olds, were assessed by means of parental interview conducted in the family home. Results: Behaviour problems were associated with the severity of ID and the severity of autistic symptomatology. Perhaps surprisingly, they were also more common in pre-pubertal than post-pubertal adolescents. Family factors such as a history of interrupted/disrupted maternal care, parental criticism of the child and aggressive parental disciplinary practices were also associated with behaviour problems, although the direction of causation was unclear. Several factors, including gender, social disadvantage and epilepsy, well established as risk factors in children without ID, were not significantly associated with behaviour problems in the present sample. Conclusion: The findings suggest that the pattern of factors associated with behaviour problems in children with "severe" ID differs from that found both in the general population and in children with mild ID.