AbstractRecords of 94 randomly selected students from the Department for the Mentally Retarded in the Special School District of St. Louis County (mean age 14.8 years) were reviewed. Forty‐nine subjects had been given the WISC (25 males and 24 females), and 45 subjects had been given the WISC‐R (31 males and 14 females). Although no statistically significant differences were found between the two groups, the WISC tested lower than the WISC‐R by an average of 1.8 points in Verbal IQ, 2.6 points in Performance IQ, and 2 points in Full Scale IQ. This finding was consistent with other studies that have indicated WISC‐WISC‐R differences of about 2 points for children over I I yea