The primary goal of this study was to establish the stability of the Wide Range Achievement Test (WRAT-3) Reading score across two annual assessments of aging individuals. Participants were classified as controls (n = 200), mild cognitive impairment (MCI; n = 137), or possible or probable Alzheimer's disease (AD; n = 41). Test-retest stability was acceptable to high for all diagnostic groups. The descriptive classification (e.g., "average") remained consistent for only 74% of participants. Results indicated that WRAT-3 Reading scores are appropriate for use with older adults, though the use of categorical descriptors to describe premorbid ability based on these scores is not supported.