"Although differences between subtest scores on the Wechsler scales are of supposed diagnostic significance, the recent WAIS Manual does not include information pertaining to norms for, or reliabilities of, any of the 55 possible difference scores among the 11 tests. On the basis of the reliabilities of the 11 tests and the intercorrelations among the tests, as given in the manual, it is possible to extract data needed for evaluating difference scores." This paper presents such data for the age range 25-34, with a detailed statistical analysis. (PsycINFO Database Record (c) 2006 APA, all rights reserved)