This paper describes an evaluation of a group intervention for reducing inappropriately expressed anger (as aggression) in people with intellectual disabilities. Group intervention was compared to a treatment as usual group consisting of people referred to the group but who had to wait to participate. The intervention used was based on the work of Novaco (1976; 1978) and Benson (1994). However, further modifications to the group that emphasized the contextual perspective of anger, such as the participants being accompanied by a support worker and more collaborative recording procedures, were devised. A reduction in expressed anger and measured levels of depression occurred after group treatment. Reductions in expressed anger were maintained at 6 and 12 months follow up. However, scores on the depression scale tended to increase on follow up. While caution must be expressed when considering these results, this type of intervention shows promise for reducing inappropriately expressed anger in people with intellectual disabilities Suggestions are made for future research and clinical practice.