The stress of multiple deployments and exposure to combat places service members at risk for posttraumatic stress disorder (PTSD), which may detrimentally affect parenting. Evidence-based parenting programs have been successful in promoting adaptive parenting practices among families exposed to stress. However, the effects of preventive interventions on parenting may vary by military parent’s PTSD. The current study includes families who participated in a randomized controlled trial of a parenting intervention for military families known as After Deployment, Adaptive Parenting Tools (ADAPT). Families were randomized to either a 14-week, group-based parenting program or a comparison group. Participants included families with 4- to 12-year-old children in which at least 1 parent deployed to Iraq or Afghanistan (N = 336; 945 individuals). Structural equation modeling was used to examine parent self-reported PTSD as a potential moderator of the relationship between intent-to-treat status and effective parenting practices 12 months postbaseline while accounting for baseline effective parenting, length and number of deployments, and family demographics. Father PTSD was a significant moderator, such that the intervention was less effective for fathers who met clinical levels of PTSD. No significant moderation effects were found among mothers. These findings may have important implications for the development of future evidence-based parenting programs.