Intellectual disability can be defined as: “significant impairment in intellectual functioning, significant impairment in adaptive/social functioning and age of onset before adulthood” (British Psychological Society, 2000). As Gordon (2010) explains, a person can be classified as intellectually disabled (ID) if they score below 70 on a reliable, standardized IQ test. Professionals rely on the Wechsler Adult Intelligence Scale, Third Edition (WAIS-III) and the Wechsler Intelligence Scale for Children, Fourth Edition (WISC-IV) to measure IQ adults and children (Gordon 2010) p 197). These two tests are very popular and have been used in the United States for several years. Strengths. These tests can help counselors by finding and comparing students' IQ scores. By having this valuable information, counselors can determine student placement and needs. IQ tests don't measure everything, but as Drummond and Jones (2010) say, "these tests measure a broad spectrum of cognitive abilities, such as reasoning, comprehension, judgment, memory, and spatial ability" ( p 155). An entire section of the ACA Code of Ethics (2005) covers assessment, evaluation, and interpretation. As stated in the code, “the primary purpose of educational, psychological, and vocational assessments is to provide measures that are valid and reliable in comparative or absolute terms. » Weaknesses. The WAIS-III and WISC-IV were rated as reliable and valid however; according to Gordon (2010), "there have been concerns about the accuracy with which these tests measure intellectual functioning in the extremities." Nagle and Lazarus (1979) conducted an evaluation of 30 participants, with IQs ranging from 55 to 75, enrolled in special education classes to compare the WAIS and the WISC. Gordon (2010) informs readers that the study found that WAIS scores were significantly higher. WAIS IQ scores were thirteen points higher, but there were significant correlations suggesting that the content was related despite the non-equivalence of scores (Gordon (2010) p 197). A study was carried out to analyze the gap between the scores of the two IQ tests. Another research study was carried out in the United Kingdom with students aged sixteen, selected from four special education schools and expected to speak English (Gordon (2010) p 198). According to Gordon (2010), the students tested were seven males and eight females who received informed consent from the principals of their current school and were provided with the WAIS-III UK and WISC-IV UK editions. The students were divided into two groups, groups one and two, and their assigned group had to determine which assessment they would take first (Gordon (2010) p. 198).