Objective: Vagal suppression is a parasympathetic physiological indicator of emotion regulation and social engagement behaviors, often measured via heart rate variability. Experiential avoidance reflects psychological inflexibility or poor emotion regulation. We tested the interaction effects of parental vagal suppression and experiential avoidance on observed parenting behaviors among combat deployed fathers. Design. We analyzed data from 92 male National Guard/Reserve members who had returned from a deployment to Iraq and/or Afghanistan since 2001. They were mostly European American, in their 30s, middle-class, and married. All fathers participated in home-based assessments with their spouses (if married) and a target child aged 4–13 years. Fathers’ vagal suppression was measured as the decrease in cardiac vagal tone (i.e., high frequency heart rate variability) from a neutral reading task to a father-child conflict resolution task. Experiential avoidance was self-reported. Parenting behaviors were observed during family interaction tasks and coded into positive engagement and withdrawal avoidance using a macro-level coding system. Results. Multiple regression analysis showed no main effects of vagal suppression on observed parenting, but interaction effects of experiential avoidance by vagal suppression on observed parenting. Specifically, among fathers with higher vagal suppression, we found no relations between experiential avoidance and observed parenting; among fathers with lower vagal suppression, we found an inverse association between experiential avoidance and positive engagement as well as a positive association between experiential avoidance and withdrawal avoidance. Conclusions. The effect of psychological inflexibility on military fathers’ parenting behaviors was moderated by vagal suppression. The findings have implications for the linkage between emotion regulation and parenting in military fathers.