Screening tools can help with the identification of intellectual disability, but little is known about who uses them. This study analysed anonymous information from 2691 users of an evidence-based, online, intellectual disability screening questionnaire for children and adolescents (CAIDS-Q) to explore the characteristics of the users and of those being screened. The users were split almost equally between parents/family members (48.6%) and professionals (49.9%), with the majority (63.8%) of the latter group being health staff. Significant differences in the characteristics of the children being screened were found, according to whether the user was a parent/family member or a professional, with the overall pattern suggesting that professionals screened children with greater complexity of needs, but about whom less was known. The screened children had a range of areas of difficulties that are common to those with intellectual disability. Implications for practice are discussed.