Active maintenance of contextual information may support good performance in a variety of tasks, but recent theories posit a secondary "reactive" mechanism which also contributes to context processing and is more transiently recruited in reaction to task demands. Both mechanisms are assumed to play a role in task performance, meaning that the newly-proposed reactive mechanism cannot be easily examined in isolation. However, the influence of reactive mechanisms may be particularly apparent in young children, a population notorious for having little regard for future consequences. The current results strongly support this claim, by demonstrating that children's performance on a novel child-adapted version of AX-CPT is driven almost entirely by reactive mechanisms. Furthermore, working memory and task-switching performance can be predicted by various indices of reactive control, extracted from measurements of reaction times, eye gaze, mental workload, and accuracy on AX-CPT, indicating an important role for reactive mechanisms even in tasks often thought to reflect active maintenance.