**5. Conclusions**

This study using ERPs to investigate performance monitoring and its development in ADHD adds to our knowledge of alterations and developmental delays in conflict processing and error monitoring in children with ADHD. Future research should be longitudinal and should include participants across the life span to determine developmental course of performance monitoring and its neural correlates in ADHD. It will also be important to identify behavioral and neural targets for intervention, both for clinical benefit as well as to develop better causal models of the development of ADHD symptoms.

**Author Contributions:** Conceptualization, Y.L., G.L.H., P.D.A and W.J.G.; Methodology, Y.L., G.L.H., and W.J.G.; Formal analysis, Y.L.; Data curation, Y.L., G.L.H., B.S.H, H.E.R.; Writing—original draft preparation, Y.L., G.L.H., W.J.G.; writing—review and editing, G.L.H., W.J.G, P.D.A., H.E.R.; visualization, Y.L.; project administration, G.H., B.S.H., H.E.R.; funding acquisition, G.L.H., P.D.A and W.J.G. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research was supported by National Institute of Mental Health grantR01 MH101493 (G.L.H., P.D.A., and W.J.G.). P.D.A. also receives support from the Alberta Innovates Translational Health Chair in Child and Youth Mental Health.

**Conflicts of Interest:** The authors declare no conflict of interest.
