"Differential Ability Scales," Second Edition (DAS-II; Elliott, 2007), was developed to measure the cognitive abilities of children and adolescents from age 2 years, 6 months to 17 years, 11 months. The test is designed to be individually administered, measuring general conceptual and reasoning ability ("g") as well as specific and diverse abilities. This information can yield a profile of relative strengths and weaknesses in cognitive functioning. The DAS-II is an updated version of the Differential Ability Scales (DAS; Elliott, 1990) and previous British Abilities Scales (Elliott, Murray, & Pearson, 1979) that include new norms of the current general population, added items and subtests, more attractive artwork, and increased ease of administration and scoring. These goals were developed based on feedback from school and clinical psychologists who had used the earlier edition. This article provides a detailed description of DAS-II and its technical adequacy.