Wechsler's hypothesis that verbal and performance factors are the major dimensions underlying the WAIS and the WPPSI subtests was directly tested by using confirmatory factor analysis. Correlated multiple-group factor analyses were performed on the WAIS subtest intercorrelations based on Wechsler's (1955) standardization sample and Doppelt and Wallace's (1955) elderly sample and for the WPPSI subtest intercorrelations based on Wechsler's (1967) standardization sample, separately for each age group. Verbal and performance factors clearly emerged in all analyses, accounting for approximately 70% of total variance for the WAIS and 60% for the WPPSI. The results provide strong support for Wechsler's hypothesis and also for the use of separate verbal and performance scores.