Intellectual assessment includes the broad range of cognitive skills and processes as measured by major intelligence tests. Intelligence testing is an integral part of the assessment process; however, it is often misunderstood. A great deal of weight is assigned to the scores, and decisions are often made that are not justified by the results. It is important for the clinician to understand the nature of the process, the types and interpretations of the scores, and the limitations, to avoid common fallacies. Two of the predominant tests, the Wechsler Intelligence Scale for Children-V and the Woodcock-Johnson IV Tests of Cognitive Abilities, are described. Some misconceptions about IQ are explained, and interpretation of intelligence test results is carefully spelled out for the clinician unfamiliar with these tools. The various scores derived from the results of intelligence tests are clarified.