The Aberrant Behaviour Checklist (ABC)
 are a caregiver report checklist designed to assess maladaptive behaviours in people with developmental disabilities, from age 6 years upwards and the content derives from work with older individuals with intellectual impairments. It therefore only just overlaps with the target age group for the review. It has 58 items and is available in 40 languages. It was used in four observational studies [18, 20, 30, 45] in the review with children as young as 3 years.