The cube imitation test was developed by Knox (1913) as a nonverbal test of intelligence. Many variants show satisfactory reliability, but performance is correlated both with Verbal IQ and with Performance IQ. Performance is impaired by cerebral lesions but unrelated to the side of lesion. Examinees describe both verbal and visuospatial strategies. In a new experiment, performance was disrupted by concurrent random generation, manual tapping, and articulatory suppression. The cube imitation test is not simply a measure of the ability to retain visuospatial information but also depends on verbal representations as well as attentional capacity. Even so, the test was central to the modern appreciation that any adequate measure of intelligence must incorporate both verbal tests and performance tests.