Background: Studies suggest that prosocial behavior, having high empathy and engaging in behaviors intended to benefit others, may predict mental health or vice versa; however, these findings have been mixed. The purpose of the current study was to examine the bidirectional relationships between prosocial behavior and dimensions of psychopathology in children. Methods: The relationships between prosocial behavior and four dimensions of psychopathology (general psychopathology, internalizing symptoms, conduct problems, and attention-deficit/hyperactivity disorder symptoms) were examined longitudinally in children 9-12 years of age from the Adolescent Brain Cognitive Development Study (N = 9122). We used a random intercept cross-lagged panel model to distinguish between stable, trait-like (between-person) and time-dependent (within-person) fluctuations across a 24-month period. Results: Between-person results revealed that prosocial behavior was negatively associated with general psychopathology and conduct problems while being positively associated with internalizing symptoms. Within-person results demonstrated that, out of four possible directional paths tested, one was significant. This path showed that greater general psychopathology and conduct problems at the first-year follow-up predicted fewer prosocial behaviors at the second-year follow-up, although the effect size was small. In contrast, prosocial behavior did not predict psychopathology dimensions for any year. Conclusions: The results of this study suggest that prosocial behaviors have stable associations with psychopathology across preadolescence; however, evidence of a directional association in which psychopathology predicts fewer prosocial behaviors in the future was only modest.