Betrayal trauma theory postulates that traumas perpetrated by a caregiver or close other are more detrimental to mental health functioning than are traumatic experiences in which the victim is not affiliated closely with the perpetrator. This study is the first to examine the concept of betrayal among a sample of individuals with a history of homelessness. A total of 95 homeless or formerly homeless adults completed the Brief Betrayal Trauma Survey, the Posttraumatic Stress Disorder Checklist-Civilian Version, the Center for Epidemiologic Studies Depression Scale the Perceived Stress Scale, and a demographics questionnaire assessing participants' histories of homelessness, health, and relationships with their families. Regression analyses were conducted to explore the associations between high betrayal (HB) and low betrayal (LB) trauma exposure, relationship with family, and physical and mental health symptoms. Exposure to HB traumas in childhood and poor family relationships predicted earlier age at first episode of homelessness, and participants who had been exposed to a greater number of traumas during childhood were more likely to be re-victimized during adulthood. Trauma exposure as an adult and earlier age of first homeless episode predicted symptoms of posttraumatic stress disorder, while trauma exposure alone predicted symptoms of depression and perceived stress. Number of medical diagnoses was associated with trauma exposure and becoming homeless at an older age. These findings emphasize that even among the most marginalized and multiply victimized individuals in our society; traumas that are characterized by a higher degree of betrayal are associated with more adverse outcomes.