The factor structure of Weschler's Adult Intelligence Scale-Revised (WAIS-R) has been a subject of controversy since the instrument was first published. We performed a series of restricted factor analyses on the 9 cohorts of the WAIS-R standardization sample in an effort to investigate the structure of this instrument. Several indices of fit were used including (a) the likelihood ratio test statistic, chi-square; (b) the LISREL Goodness of Fit Index; (c) the normed-fit index, with both a null and informed baseline; (d) the rescaled Akaike and Schwartz criteria; and (e) the root mean square residual. Results indicated that a 3-factor model accounts best for the relations among the 11 WAIS-R subtests in 8 of the 9 standardization cohorts. The 3 factors correspond to the Verbal Comprehension, Perceptual Organization, and Memory/Freedom From Distractibility factors that have been identified in the WAIS. Factor comparison procedures were used to test the generalizability of this structure in psychiatric and medical samples.