Intellectual impairment or disability is a lifelong condition with difficulties in adaptive behaviour and cognitive functioning evident since childhood. Intellectual disability, also called learning disability in the UK, has been defined as an IQ below 70 combined with functional limitations. The focus of this report is mostly on people above this threshold, who may have borderline intellectual impairment. It is accepted that testing for intellectual impairment is subject to error due to variations in cultural norms or constructs. For example, measures that assess IQ may lead to fewer people identified as having an intellectual impairment than measures that identify people based on limitations in adaptive functioning.