Cognitive control shows two main developmental trends: greater self-directedness (i.e., children need less external scaffolding) and greater proactiveness (i.e., children increasingly anticipate and prepare for upcoming cognitive demands). The present study examined potential links between these major developmental transitions. Specifically, it used EEG oscillations to investigate the extent to which children, like adults, engage self-directed control in a proactive fashion, and whether age-related changes reflect progress in task selection, motor preparation, or both. Five-6-year-olds, 9-10-year-olds, and adults performed a voluntary task-switching paradigm in which visual support for past actions was manipulated. Both children and adults showed greater frontolateral delta/theta power and lower central mu power on switch than repeat trials, but visual support differentially affected these oscillatory markers across age groups. Children already engage self-directed control proactively from 5 to 6 years of age in the voluntary task-switching paradigm, albeit differently than adults, suggesting close links between self-directed and proactive control developments.