<p dir="ltr">Military families are a unique context as they experience separation from the service member who is away from the family for a considerable duration of time for a job that puts them at risk of serious injury or death. Service members returning from deployments may display a variety of mental health difficulties including post-traumatic stress disorder, especially when they have combat experiences. Applying a family systems framework, this thesis examined the associations between both service members’ and significant others’ PTSD symptoms, their ineffective arguing, and their reports of their children’s externalizing behaviors across three time points during reintegration, or the stage in the deployment cycle when the service member returns to the family. The study tested hypotheses that these would decline over time, and that initial levels and the rate of change in ineffective arguing would mediate the effect of parental PTSD at Time 1 on children’s externalizing behaviors at Time 3. Using data from service members and significant others in 71 families (142 individuals), I estimated multilevel models using both mixed and the structural equation frameworks. I found that parental PTSD and ineffective arguing were stable across reintegration, with considerable inter-individual variation in these at baseline. There was a decrease in children’s externalizing behaviors across time. There were also significant differences in parents’ rating of children’s externalizing behaviors. I did not find evidence for mediation but did find an association between parental PTSD and baseline levels of ineffective arguing. Results suggest that while parental stress is linked with the couple’s functioning, there may be protective factors within families that act as sources of resilience for the children.</p><p><br></p>