Dual tasking is an integral part of everyday activities for children. Therefore, as with the other aspects of child development—motor, cognitive, perceptual, psychological, and behavioral—it is important to understand the maturation process of dual-tasking skills in children. Characterizing age-related changes in children’s dual-task performance has been problematic, because differences in dual-tasking ability are confounded by age differences in abilities in the relevant single-task performances. The effect of age on dual-tasking ability was examined in 221 typically developing children aged 5–8 years using two motor–cognitive dual-task paradigms: walking while performing an n-back cognitive task, and drawing a trail while performing an n-back cognitive task. The test–retest reliability of the dual-task paradigm was examined by re-assessing 50 participants after 1 month. Individual differences in single-task performance were controlled for, so that any age differences in dual-task costs could not be attributed to differences in single-task performance. There were no age-related differences in dual-task cost of any task (p > 0.05). However, the dual-task cost of trail-making was significantly greater than the dual-task cost of walking when performed under similar cognitive loads (p < 0.0001). The intra-class correlation coefficient ranged from 0.71 to 0.92 for all dual-task performances. The results suggest that previously reported age differences in dual-task costs in young children may have been driven by developmental differences in single-task ability, and that general task coordination ability is comparable in children 5–8 years of age.