This article reviews the prevalence of co-occurring posttraumatic stress disorder (PTSD) and substance use disorders (SUDs) in the veteran population. Recommendations regarding how to better understand, engage, and retain veterans with PTSD/SUDs in treatment are presented through an ecological perspective that takes into account the multiple systems and worldviews, including culture, ethnicity, family, and military culture, that are transacting with the individual. A case example illustrates the multifaceted