The research suggests that young offenders with an intellectual disability (ID) may not always be identified within youth justice services. This pilot study assessed some aspects of the validity of a screening tool, the Child and Adolescent Intellectual Disability Screening Questionnaire (CAIDS-Q), in UK forensic settings, using data from 23 individuals. The CAIDS-Q had positive and negative predictive power of 100%. In addition, a significant difference was found in CAIDS-Q scores between those with and without an ID, with the latter group scoring significantly higher, indicating discriminative validity. A significant positive relationship was found between full-scale IQ and CAIDS-Q scores, indicating convergent validity. The pilot study suggested that the CAIDS-Q may represent a valid screening tool to identify those young offenders who are likely to have an ID. Limitations and implications of the pilot are discussed.