Neuropsychological studies have shown differences in performance on inhibition tasks across age groups, and neuroimaging studies have highlighted increasing maturation into early adulthood of the frontal networks responsible for inhibitory control. The aims of the current study were to report developmentally sensitive response time and error data from healthy female children and adolescents on the Hayling test, and to explore the appropriateness of the adult-normed scaled score boundaries when applied to children and adolescents. Participants were female English speakers (mean age of 15.11, SD = 1.68 years, range of 11.92–17.67 years, mean IQ of 103.96, SD = 11.04). The sample was divided according to age and assessed on Section 1 (verbal initiation) and Section 2 (verbal inhibition) of the Hayling test. A significant overall difference was found between the four age groups on Section 1 time scaled scores. However, post hoc analyses revealed that the only significant effect was between the 11- to 12-year-olds and the 15-year-olds, with the younger group having longer response times. On Section 2, there were no significant differences between the age groups in raw or scaled response times, nor were there significant differences in the number of errors made (raw or scaled score). The findings from the current study suggest limited support for evidence of a developmental trend in inhibition of prepotent responses.