Background. Previous research has suggested that behavioural problems displayed during the pre-school years are best understood as undifferentiated difficulties in manageability. The present study explored this issue, by examining the structure of British parents' ratings of their pre-school children's behavioural problems.

Method. The 19-item Behavioural Checklist (BCL; Richman, 1977) was completed by 1047 parents of 3-year-old children taking part in an epidemiological survey of child development.

Results. Factor analysis revealed six factors representing poor social adjustment, poor emotional adjustment, sleep problems, over-activity/inattention, eating problems and soiling. When these scores were used as a basis for cluster analysis, problem types clustered around six centres. The first, and largest, grouping was of children with no problems. Three further large groupings displayed specific but moderate problems (over-active, timid, and naughty children). The final two groupings displayed more extreme problems including anti-social behaviour. In one group these were accompanied by severe emotional problems and in the other by signs of hyperactivity. The reliability and validity of these clusters was supported. Parental ratings of behaviour problems taken when the children were 8-years-old suggested that the children in the hyperactive/conduct group were likely to have continued difficulties.

Conclusion. This paper argues against the homogeneity of pre-school behaviour problems but supports the idea that problems of a clinically significant level are likely to be co-morbid, with either problems of emotional regulation (neurotic) or those of behavioural regulation (hyperactive) accompanied by problems of conduct.