Primary school aged children with severe learning disabilities and behavioural problems were identified from those attending special needs schools in three adjacent Inner London boroughs. In two of the boroughs their parents/carers were randomly allocated to receive 5-7 group- or individually-based intervention sessions aimed at preventing or reducing their child's behaviour problems; teaching and support staff at their schools received a 2-day workshop with the same aims. Children in the third borough served as a “no treatment” control group. Follow-up assessments were carried out shortly after the interventions were completed and 6 months later. Individually-based intervention was superior to group-based intervention in acceptability, attendance, levels of participant satisfaction and the likelihood of reported behavioural improvement. Within the individual intervention group, behaviours that had been targeted for intervention were more likely to show improvements than those that were untargeted. However, in spite of these improvements, there were no significant differences between groups in the absolute frequency or severity of the child's behaviour problems at either post-intervention assessment, and reductions in levels of parental distress noted on completion of the interventions were no longer apparent 6 months later.