The main purpose of the study was to investigate the role military and civilian social support may play in moderating the relationship between stress and mental and physical health during post-deployment reintegration among Army National Guard (ARNG) members. Secondary data were used from a large longitudinal study in which face-to-face structured interviews were conducted with ARNG members at six months post-deployment. Hierarchical multiple regression analyses were conducted to assess the contribution of reintegration-related stress on self-reported mental health and Post-traumatic Stress Disorder (PTSD) symptoms at six months post-deployment. Results indicated no significant association between self-reported physical health and reintegration stress, social support, or mental health. Contrary to expectations, neither civilian, nor military, social support moderated the relationship between reintegration stress and perceived mental health or PTSD symptoms. Reintegration stress was associated with lower self-reported mental health. In contrast, civilian social support was associated with higher levels of self-reported mental health. Findings from the current study suggest civilian, but not military, social support is a critical protective factor for perceived mental health and lower PTSD symptoms among ARNG members during the post-deployment reintegration time period.