Aim: To evaluate the psychometric properties of the Child and Adolescent Intellectual Disability Screening Questionnaire (CAIDS-Q) in paediatric neurodevelopment clinics. Method: Participants were 181 children (aged 6–18y) attending paediatric services in Scotland, divided into three age groups according to previous CAIDS-Q standardization cut-off scores. Fifty-four children (37 males, 17 females; mean age 117mo [SD 29.9mo]) met the criteria for intellectual disability and 127 did not (88 males, 39 females; mean age 120.1mo [SD 32.7mo]). A number of psychometric properties of the CAIDS-Q were evaluated, including test–retest and interrater reliability, convergent validity, sensitivity, specificity, and positive and negative predictive values based on existing cut-off scores. Results: Significant positive relationships were found for all three age groups between CAIDS-Q scores and measures of intellectual and adaptive functioning. Test–retest reliability ranged from ‘moderate’ to ‘almost perfect’, whereas interrater reliability ranged from ‘fair’ to ‘almost perfect’. Sensitivity and positive predictive value were 100% for all groups and specificity was between 83% and 94%, depending on age. Negative predictive values ranged from 75% to 91%. Interpretation: The CAIDS-Q appears to show psychometric properties that support its use as a screen for intellectual disability in paediatric neurodevelopmental settings. What this paper adds: The Child and Adolescent Intellectual Disability Screening Questionnaire showed good psychometric properties. It identified all participating children who met the criteria for intellectual disability. Between 83% and 94% of children without intellectual disability were also correctly identified.