The Cognitive Assessment System, Second Edition (CAS2) is a well-researched, norm-referenced measure of cognitive ability based on the well-researched cognitive/neuropsychological theory called PASS (Planning, Attention, Simultaneous, and Successive). The CAS2 was designed to measure cognitive processing abilities important for a broad range of differential diagnoses and instructional planning in individuals ages 5-0 through 18-11. CAS2 provides practitioners with a valid and reliable tool to evaluate children’s strengths and weaknesses in important areas of cognitive processing.