Many young children present to the podiatric physician with the complaint of aching legs. Many of these children are clinically assessed as having a pronated foot posture. This foot posture is thought to be deleterious and is often treated with in-shoe devices such as triplane wedges or orthoses. Intervention aiming to reduce the amount of foot pronation in both stance and gait has been reported by parents and children to reduce, and in many cases eliminate, the episodes of aching legs. To test this theory and establish a degree of causality, a single-case experimental design was used in conjunction with age-appropriate pain scores for the children and independent parental ratings. Single-case experimental design is a useful research tool for the clinical practice setting that can identify cause-effect relationships and obviates large sample sizes. Eight complete single-case experimental designs were performed in the clinical setting. The in-shoe intervention proved efficacious for children with a pronated foot posture and aching legs. These findings may provide the impetus for a more rigorous examination of the possible relationship between pronation and "growing pains."