A number of critical issues concerning the assessment of children with intellectual disabilities, including definitional problems, psychometric factors, and practical difficulties, are raised in this article. It is suggested that school counsellors and psychologists should consider these issues when assessing children with probable or known intellectual disabilities, particularly when using IQ tests. The use of adaptive scales as an additional means of defining and measuring intellectual disability is also examined. Although no ideal means of formally assessing children with intellectual disabilities is put forward, a range of concerns is explored and some suggestions for appropriate additions and caveats to present practice are proposed.