Research has shown an increased frequency of suicidal behaviors in those with PTSD, but few studies have investigated the factors that underlie the emergence of suicidal behavior in PTSD. Two theories of suicide, the Cry of Pain and the Schematic Appraisal Model of Suicide, propose that feelings of hopelessness, defeat, and entrapment are core components of suicidality. This study aimed to examine the association between suicidal behavior and hopelessness, defeat, and entrapment in trauma victims with and without a PTSD diagnosis. The results demonstrated that hopelessness, defeat, and entrapment were significantly positively associated with suicidal behavior in those with PTSD. Hopelessness and defeat were also significantly positively associated with suicidal behavior in trauma victims without PTSD. In those with PTSD, the relationship between suicidal behavior and hopelessness and entrapment remained significant after controlling for comorbid depression. The findings provide support for the contemporary theories of suicidality and have important clinical implications.