BackgroundThe Behaviour Problems Inventory-Short Form (BPI-S) is a spin-off of the BPI-01 that was empirically developed from a large BPI-01 data set. Inthis study, the reliability and factorial validity of the BPI-S was investigated for the first time on newlycollected data from adults with intellectual disabilities. MethodsThe sample consisted of 232 adults with intellectual disabilities who represented all levels of intellectual functioning. They were recruited at several day programs in the USA (n=148) and the UK (n=84). ResultsWe found acceptable reliability in terms of internal consistency, inter-rater agreement and test-retest reliability. Confirmatory factor analysis validated the three BPI-S subscale structure. ConclusionsWe corroborated the factor structure underly-ing the three subscales and found the BPI-S to have adequate to good psychometric properties in a newly collected sample of adults with intellectual disabilities.