OBJECTIVE: Unlike adults, children often fail to coordinate their behavior away from unnecessary cognitive demands to conserve effort. The present study investigated whether greater conflict monitoring may contribute to metacognitive monitoring of cognitive demands, which in turn may support greater cognitive demand avoidance with age. METHOD: Electroencephalogram data were recorded while 54 adults and fifty-four 5- to 10-year-old children completed a demand selection task, where they chose between versions of a task with either higher or lower demands on cognitive control. RESULTS: Both adults and children avoided the high-demand task, showing that, in some circumstances, children as young as 5 years can avoid unnecessary cognitive demands. Critically, midfrontal theta power predicted awareness of cognitive demand variations, which in turn predicted demand avoidance. The relationship between midfrontal theta power and demand awareness was negative and did not change between age groups. CONCLUSION: Together, these findings suggest that metacognitive monitoring and control are based in part on conflict monitoring in both children and adults. (PsycInfo Database Record (c) 2025 APA, all rights reserved).