Cognitive control enables goal-oriented adaptation to a fast-changing environment and has a slow developmental trajectory that spans into young adulthood. The specifics of this development are still poorly understood, as are the neurodevelopmental mechanisms that drive it. In a cross-sectional sample of participants 8-19 years old (n = 108), we used blind source separation of EEG data recorded in a Flanker task to derive electrophysiological measures of attention and the processing of cognitive conflict, including a frontal negative component corresponding to the N2 and a parietal positive component corresponding to the P3. Additionally, we examined multiple behavioral measures of interference control derived from the Flanker, Stroop, and Anti-saccade tasks. We found a positive association between age and the amplitude of the parietal positive component, while there was no relationship between age and the amplitude of the frontal negative component. A stronger frontal negative amplitude was, however, ageindependently related to better performance on both Stroop and Anti-saccade measures of interference control. Finally, we examined post-conflict behavioral adjustment on the Flanker task. A Gratton effect was found with slower reaction times on current congruent and better accuracy on current incongruent trials when preceded by incongruent as opposed to congruent trials. The Gratton effect on accuracy was positively associated with age. Together, the findings suggest a multifaceted developmental pattern in neurocognitive mechanisms for conflict processing across adolescence, with a more protracted development of the parietal positive compared to the frontal negative component.