Inhibitory control is a core executive function that develops during childhood and is measured with tasks that require the inhibition of a dominant response. The current study examined the diagnostic value of using response accuracy and latency in a simple inhibitory control test, the computerized Pointing-Stroop Task (cPST), for kindergarten children. The cPST was completed by 135 children, ages 3 through 6 years with diverse national and cultural backgrounds. In explanatory response models, item difficulties and time intensities could be predicted very reliably by congruency and item position, with incongruent responses causing more errors and longer response latency. Moreover, the prediction of fluid intelligence (a close correlate of inhibitory control) from children's performance in the cPST was enhanced by using response accuracy and response latency, which had a multiplicative effect, indicating that efficient (accurate and fast) inhibitory control is related to fluid intelligence. These results suggest that measuring the efficiency of inhibitory control in young children is a more appropriate assessment than using either response accuracy or response latency.