Objective: To empirically examine similarities and differences in the signs and symptoms of posttraumatic stress disorder (PTSD) and moral injury and to determine if the combination of these 2 constructs is associated with increased risk for suicidal thoughts and behaviors in a sample of U.S. National Guard personnel. Method: 930 National Guard personnel from the states of Utah and Idaho completed an anonymous online survey. Exploratory structural equation modeling (ESEM) was used to test a measurement model of PTSD and moral injury. A structural model was next constructed to test the interactive effects of PTSD and moral injury on history of suicide ideation and attempts. Results: Results of the ESEM confirmed that PTSD and moral injury were distinct constructs characterized by unique symptoms, although depressed mood loaded onto both PTSD and moral injury. The interaction of PTSD and moral injury was associated with significantly increased risk for suicide ideation and attempts. A sensitivity analysis indicated the interaction remained a statistically significant predictor of suicide attempt even among the subgroup of participants with a history of suicide ideation. Conclusion: PTSD and moral injury represent separate constructs with unique signs and symptoms. The combination of PTSD and moral injury confers increased risk for suicidal thoughts and behaviors, and differentiates between military personnel who have attempted suicide and those who have only thought about suicide.