Background: The extent to which people with intellectual disabilities (ID) set fires is difficult to ascertain. However, services working with people with ID and offending or quasi-offending histories are increasing the amount of attention that they give to this difficult and perplexing issue. This is due to the real and perceived threat that it presents to society and the seriousness with which it viewed by the criminal justice system. Aim: Against this background there is very little available in the research literature concerning treatment interventions for fire-setting behaviour in this client group, and even less regarding their effectiveness. Method: In the current study 14 men and women with mild and borderline ID, convictions for arson and detained in a hospital low secure service were offered and completed a broadly cognitive behavioural, approximately 40-session group-based intervention. The treatment was aimed primarily at reducing fire interest and attitudes associated with fire-setting behaviour. Participants were assessed pre- and post-treatment on a number of fire-specific, anger, self-esteem and depression measures. Results: Following treatment, significant improvements were found in all areas assessed, excepting depression. Despite the limitations of the study design, the results provide encouragement and some guidance to practitioners who are required to develop interventions for this challenging, yet much neglected client group.