The present study explores the neural basis of the development of inhibitory control by combining functional neuroimaging with a parametric manipulation of a go–nogo paradigm. We demonstrate how the maturation of ventral fronto–striatal circuitry underlies the development of this ability. We used event–related fMRI to examine the effect of interference on neural processes involved in inhibitory control in children and adults. Nogo trials were preceded by either 1, 3 or 5 go trials and then compared to one another. Both children and adults showed an increase in errors with increasing interference. Successful response inhibition was associated with stronger activation of prefrontal and parietal regions for children than for adults. In adults, activation in ventralprefrontal regions increased with increasing interference from go trials. Unlike adults, the circuitry appeared to be maximally activated in children when suppressing a behavioral response regardless of the number of preceding responses. Furthermore, activation in ventral fronto–striatal regions correlated with both age and performance. These findings suggest that immature cognition is more susceptible to interference and this is paralleled by maturational differences in underlying fronto–striatal circuitry.