The Freedom from Distractability Index (FFD) on the Wechsler Intelligence Scale for Children- Third Edition (WISC-III) is an index score comprised of the sum of the scores on the Arithmetic and Digit Span subsets. Although the FFD is often interpreted as a measure of attention and concentration, there are a number of other possible explanations for performance in this scale, including anxiety, number facility, auditory short-term memory, and working memory. Comparisons were made across ADHD and non-ADHD groups of children on several measures used to assess attention in children between the ages of 9-15. Results indicated the FFD index shares greater variance with measures of achievement than of attention or memory. Additionally, correlations with measures of attention were low, with the exception of the CMS Attention/Concentration scale. (Contains 15 references and 1 table.) (Author)