The Wechsler Adult Intelligence Scale-Revised (WAIS-R) and the Wechsler Memory Scale-Revised (WMS-R) are the most commonly used intelligence and memory scales in both clinical and neuropsychology. In 1997, updated versions of these instruments (the WAIS-III and WMS-III) were published. Because of the extensive use of the WAIS-R and WMS-R in the field and the body of accumulated research, there is naturally some reluctance by clinicians and researchers to update to the new versions. It is sometimes difficult for clinicians who test individuals on repeated occasions to switch over to the new versions of the scales because of the difficulty of interpreting score discrepancy between the 2 versions. Researchers, especially those conducting longitudinal research, have a similar difficulty in changing measurement devices because of the possible threat of internal validity. This article reviews the substantive revisions of the scales and outlines those issues that users should take into consideration when updating to the new versions.