Background: Suicide is a leading cause of death among US veterans. Associations between depression, posttraumatic stress disorder (PTSD), and suicidal behaviors have been found in this population, yet minimal research has explored how manifestations of self-injurious behavior (SIB) may vary among different diagnostic presentations. Aims: This study aimed to identify clinically useful differences in SIB among veterans who experience comorbid mood disorder and PTSD (CMP) compared with those who experience a mood disorder alone (MDA). Method: Participants were 57 US military veterans who reported an incident of intentional SIB. The semistructured Post Self-Injury/Attempted Self-Injury Debriefing Interview was used to examine characteristics of the SIB. Results: Veterans diagnosed with CMP were more likely than those with MDA to (a) report that the SIB was impulsive and (b) to be under the influence of substances at the time of self-injury. Limitations: Generalizability may be limited by small sample size and predominantly European American, male demographics. While highly relevant to routine clinical practice, caution is recommended, as study diagnoses were attained from medical records rather than structured interviews. Conclusion: Safety planning that emphasizes protection against impulsive suicide attempts (e.g., means restriction) may be especially important among veterans with comorbid mood disorder and PTSD.