The number of children currently experiencing a psychopathological disorder is growing quickly. It is essential to identify different causes of this to understand better how to prevent psychopathology in children. Prior research has shown that different emotion dynamics between the parent and child, like rigidity, flexibility, or synchrony, have been found to be associated with psychopathology. Synchrony or the matching of positive emotions in a dyad has been found to be protective against symptoms of psychopathology for children. In addition, flexibility, or the number of emotion transitions between a dyad, has also been shown to be protective against symptoms of psychopathology, although rigidity or fewer emotion transitions in a dyad has been predictive of psychopathology. However, this research has been almost entirely focused on infants and toddlers as well as adolescents, with little research being done on synchrony, rigidity, and flexibility in middle childhood. This study aimed to identify whether synchrony, rigidity, and flexibility are predictive or protective of internalizing, externalizing, and ADHD symptoms of psychopathology in middle childhood. Data was collected from a sample of 762 ethnically diverse children from the Arizona Twin Project that were assessed at ages 9 (Mage=9.71, SD=.93) and 11 (Mage=11.65, SD=1.04). Children and their parents were examined when the child was 9 during a video-recorded discussion task to determine rigidity, flexibility, and synchrony that was coded by iMotion Affectiva. Internalizing, externalizing, and ADHD symptoms of psychopathology were measured at ages 9 and 11 both through parent-report and child report. Results found that during a conflict-based discussion, synchrony and negative co-regulation between the parent and child were protective against internalizing, externalizing, and ADHD symptoms of psychopathology both concurrently and longitudinally. Rigidity and flexibility between the parent and child were not found to be associated with psychopathology. These findings can help inform future parenting programs or influence parent child interactions by teaching the importance of using positive emotions during negative conversations with parents.