Suicide is a significant public health concern, and, specifically, the veteran population has exhibited a 22% higher risk of death by suicide than the general population (Department of Veterans Affairs, 2017). The interpersonal psychological theory of suicide (IPTS; Joiner, 2005) appears to be the most widely researched theory to examine factors associated with suicidal ideation. The IPTS applies to veteran suicidal ideation in that veterans may feel they are burdensome to others or that they do not belong following their transition from active duty. The current study sought to (a) identify the prevalence and correlates of the IPTS constructs perceived burdensomeness and thwarted belongingness; (b) examine the main and interactive effects of these constructs on suicidal ideation; and (c) examine their indirect effects in the associations between posttraumatic stress disorder (PTSD) symptomatology, depressive symptomatology, and substance use with suicidal ideation in a sample of veterans in PTSD residential treatment (N = 125). Regression results demonstrated that perceived burdensomeness was significantly associated with suicidal ideation, β = .50, p < .001; however, thwarted belongingness and the interaction of the two were not. In the models of indirect effects, perceived burdensomeness emerged as the only significant indirect effect in the association between PTSD symptomatology and suicidal ideation, β = .01 (SE = .00), 95% CI [.0050, .0149], as well as between depressive symptomatology and suicidal ideation, β = .02 (SE = .01), 95% CI [.0109, .0311]. Study limitations and future directions are also discussed.