The fifth edition of the Stanford-Binet test went through significant reformulation of its item content, administration format, standardization procedures, and theoretical structure. Additionally, the test was revised to measure five factors important to intelligence across both verbal and nonverbal domains. To better understand these substantial revisions, the underlying factor structure of the instrument was investigated using both exploratory and confirmatory factor analysis procedures across five age groups tested by the publishers. Analyses were conducted using 4,800 cases included in the instrument standardization. Results suggested that the verbal/nonverbal domains were identifiable with subjects younger than 10 years of age whereas a single factor was readily identified with older age groups. (Contains 3 tables.)