The purpose of this study was to investigate the development of inhibitory control, to determine whether sustained attention predict inhibitory control and to examine the moderating role of gender in the sustained attention-inhibitory control relationship among 8- to 12-year-olds. Sustained attention and inhibitory control abilities were assessed by using Cancellation tasks, Stroop test and Go/NoGo task. As expected, children with higher sustained attention abilities exhibited greater inhibitory control. Moreover, inhibitory control increased across age. Next, interaction analyzes showed that gender moderated the correlation between Cancellation and Go/NoGo scores. These results add to the understanding of the development of sustained attention and inhibitory control during middle childhood.