The study outlines the evaluation of an intellectual disability screening tool, the "Child and Adolescent Intellectual Disability Screening Questionnaire" ("CAIDS-Q"), with two age groups. A number of aspects of the reliability and validity of the "CAIDS-Q" were assessed for these two groups, including inter-rater reliability, convergent and discriminative validity. For both age groups, a significant positive relationship was found between full scale IQ and "CAIDS-Q" score, indicating convergent validity. Significant differences were found in the "CAIDS-Q" scores between those with and without an intellectual disability, with the former group scoring significantly lower. The sensitivity and specificity of the "CAIDS-Q" were above 96.7% and 85.5% respectively for the younger group and 90.9% and 94.9% respectively for the older group. Limitations and implications of the study are discussed.