People with Intellectual Disability (ID) have cognitive impairments that affect their level of functioning the causes of which are multiple and often unknown. Behavioural difficulties are common among people with ID. Attention Deficit Hyperactivity Disorder (ADHD) is recognised more among people with Intellectual Disability and could be a cause of problem behaviours. Screening and assessing for ADHD in people with ID is difficult because of the paucity of robust assessment tools and diagnostic criteria.