This study examines the relation between the error-related negativity (ERN) and post-error behavior over time in healthy young adults (N = 61). Event-related brain potentials were collected during two sessions of an identical flanker task. Results indicated changes in ERN and post-error accuracy were related across task sessions, with more negative ERN associated with greater improvements in post-error accuracy. This relationship was independent of any cross-sectional relationships between overall task performance, individual difference factors, including personality and self-efficacy, and indices of self-regulatory action monitoring. These results indicate that the relation between ERN and post-error accuracy remains intact and consistent regardless of variation in this set of individual difference factors previously associated with both of these indices of self-regulatory action monitoring, providing support for the strength, robustness, and persistence of this relationship in the process of adaptively controlling behavior to enhance task performance. (Contains 5 tables and 3 figures.)