Military veterans have greater exposure to adverse childhood experiences (ACEs) than civilians and many also encounter warfare exposures, which can increase the likelihood of mental health problems. The purpose of this study was to test an interaction between childhood traumas and warfare exposures on the mental health of a sample of nearly 10,000 new post-9/11 veterans. Results revealed that male veterans exposed to one or two ACEs, but no warfare, were more likely to experience anxiety, depression, suicidal thinking, and angry outbursts than the reference group (i.e., no ACEs and no warfare exposure). Female veterans exposed to one or two ACEs, but no warfare, were only more likely to experience suicidal thinking. Male and female veterans exposed to three or more ACEs and no warfare were more likely to experience probable posttraumatic stress disorder (PTSD), anxiety, depression, suicidality, and angry outbursts. Among those veterans who experienced corollaries of combat only (e.g., seeing someone killed or seriously wounded), male, but not female veterans were more likely to have probable PTSD, anxiety, and depression. Veterans exposed to warfare (i.e., combat and the corollaries of combat), irrespective of ACEs exposure, were the most likely to report mental health symptoms. Implications for community-based mental health services are discussed.adverse childhood experiences, alcohol misuse, anxiety, combat exposure, depression, PTSD, veteran mental health 1 | BACKGROUND Currently, there are more than 20 million military veterans in the United States, including 2.6 million who have served since 9/11. The veteran population is projected to grow to 5 million by 2025 (National Center for Veterans Analysis & Statistics, 2018). The majority of these veterans do not experience ongoing adjustment or reintegration problems and make a successful transition back to their communities (Tsai et al., 2015). However, a substantial minority report struggles with reintegration. Difficult transitions from military to civilian life have the potential to place a tremendous burden on veterans and their families, communities, and healthcare systems.Veterans, as they transition out of active duty service, are returning in large numbers to civilian communities.