The present study investigated the stability of scores on the WISC-IV and WAIS-IV over an approximate six-year period. Previous research using older versions of the WISC and WAIS have suggested that these scales demonstrate strong stability of scores. Since research that has compared the stability of scores between the WISC-IV and the WAIS-IV is presently limited, the present study was necessary. The 40 participants in this study were previously identified special education students, who were selected utilizing archival data from a suburban school district. Test-retest stability was investigated using correlation coefficients and t-tests. The FSIQ and indexes demonstrated-moderate-to-strong-stability, with a low of 0.59 for the PSI and a high of-0.84 for the FSIQ. Subtest correlations ranged from a low of 0.34 for Matrix Reasoning to a high of 0.71 for Block Design. Statistically significant differences were found for the PSI and for the Similarities, Matrix Reasoning, Coding, and Symbol Search subtests. Analyses of individual scores indicated that the majority of the sample (65%) remained in the same classification category from initial testing to reevaluation testing. Frequency distributions noted that 77.5% percent of the sample demonstrated an approximate +/-10 point change in their FSIQ. Implications for School Psychologists and directions for future research are discussed. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com/en-US/products/dissertations/individuals.shtml.]