The differential outcome effect (DOE) refers to the increase in speed of acquisition and terminal accuracy that occurs in conditional discrimination learning when two or more stimuli are correlated with a particular outcome. Previous studies demonstrated the benefits of the DOE in preschool children. In two experiments we extended the DOE methodology to older children and tasks of different difficulty. Experiment 1 indicated that the DOE procedure improved conditional discrimination performance of 4- to 7-year-old children. However, this effect was not present in children aged 8 years. In Experiment 2, we increased the difficulty of the task and demonstrated that these children in the differential outcome condition performed significantly better on this complex version of the discriminative task than those in the matched control group. It is proposed that the DOE is a general effect that is not limited to early stages of development and that the difficulty of the task is an important variable to consider when a differential outcome procedure is used.