The relations among assessments of working memory (WM) and a range of complex cognitive abilities were examined. In 2 experiments participants completed 2 WM tasks designed to assess verbal and nonverbal WM, as well as assessments of verbal intelligence, nonverbal intelligence, and academic achievement. Verbal WM had no relationship with nonverbal intelligence, whereas nonverbal WM had no relationship with verbal intelligence and academic achievement. A reanalysis of P. C. Kyllonen & R. E. Christal (1990, Experiment 1) is reported in which multiple indicators of WM were used to identify verbal and nonverbal WM factors; both of these WM factors were heavily saturated with a second-order factor, g (61% and 69%, respectively). Convergent and discriminant validation of the multidimensionality of WM was found in the patterns of correlations among the first-order Working Memory, General Knowledge, and Speed factors.