Equations for prorating Wechsler Memory Scale-Revised General Memory (GM) and Delayed Recall (DR) index scores ([Woodard and Axelrod, 1995]) were confirmed in the [Mittenberg et al. (1992)] normative WMS-R sample of 50 subjects between the ages of 25 and 34, and confirmed in a separate clinical sample of 30 patients with closed head injury who were age, education, and gender matched with 30 subjects from that normative sample. Predicted GM and DR index scores fell within 6 points of the obtained scores for 98% of the [Mittenberg et al. (1992)] sample and 93% to 100% of the matched head injury and normative samples, despite statistically significant differences between these groups in obtained GM, DR, and percent retention of LM I and II and VR I and II. Six points is well within the standard error of measurement of these index scores. These findings confirm the earlier cross-validation results reported by [Axelrod et al. (1996)] in a mixed sample of traumatic brain injury and other neurological insult, and suggest that this method of estimating weighted score sums for WMS-R General Memory and Delayed Recall indices may be safely used in normative samples of patients in this age range as well as neurologically compromised patients without significantly impacting index score accuracy.