Challenging behaviour has played a major role in why some people with severe learning disabilities fail to live in the community as normal citizens. More than one million people with intellectual disabilities also show additional problematic behaviours (Hill and Bruininks, 1984). These behaviours include aggression, self-injury, inappropriate social or sexual conduct, and destructiveness. The combination of these intellectual and behavioural disabilities is putting carers and family members at risk (Emerson, E. et al. (1999) Clinical Psychology and People with Intellectual Disabilities,Cambridge United Press). Behavioural psychology has played an influential part in guiding thinking and practice with regard to the assessment and treatment of challenging behaviours, and the introduction of such interventions have led to a decrease in the number of incidents over the past few decades (Emerson, E. et al. (1999) Clinical Psychology and People with Intellectual Disabilities, Cambridge United Press ). …