Among adult and adolescent populations, the personality trait of honesty-humility (HH) has been linked to aggression. For example, adults low in HH have been found to exhibit higher levels of workplace delinquency and revenge motivation, and adolescent low in HH are more likely to bully others. However, there is a paucity of research examining this relationship in children and youth, and how these relationships develop over time. The current study addressed these gaps in the literature by assessing whether HH and impulsivity are independently associated with aggression in children Grades 3 through 8 (N = 1201). Using data from the two waves of a longitudinal project, autoregressive crossed-lagged path analysis was used to examine the bidirectional relationships between HH, impulsivity, and aggression over a 1-year period. Results revealed significant bidirectional relationships between HH and aggression, such that lower scores of HH at Time 1 were associated with higher scores of aggression at Time 2 and vice versa. Similarly, higher scores of impulsivity at Time 1 were associated with higher scores of aggression at Time 2 and vice versa. In addition, these relationships were strongest in boys and at higher ages. Consistent with research in other populations, these results indicate that low HH and high impulsivity are linked to aggression in children and youth. Further, our results demonstrate that HH and impulsivity bidirectionally impact aggression as one age, suggesting a need for early intervention. [ABSTRACT FROM AUTHOR]