A large sample of 7-year-old children (n = 940) was rated by teachers using the Rutter Child Scale B, a 26-item questionnaire covering a variety of behavioural problems. A factor analysis of the data revealed three main factors of interest, identified as aggressiveness, hyperactivity and anxiety-fearfulness. Measures based upon these factors had a reasonably high level of reliability and were moderately stable over a 2-year interval. An analysis of the relationship between these three behavioural measures and some cognitive measures indicated that only hyperactivity was negatively associated with cognitive ability. However, both hyperactivity and aggressiveness were related to adversity in the child's family background. The findings suggest the usefulness of distinguishing between aggressive and hyperactive dimensions of behaviour.