This case-control study enrolled 226 maladjusted soldiers and 229 controls to investigate the impact of the interpersonal-psychological theory of suicide, alexithymia, personality, and childhood trauma on suicide risk among Taiwanese soldiers. Assessments included the Toronto Alexithymia Scale, Eysenck Personality Inventory, Mini-International Neuropsychiatric Interview, and Brief Symptom Rating Scale. In addition to thwarted belongingness and perceived burdensomeness, other risks included less extraversion with higher neuroticism, higher alexithymia, poor academic performance, domestic violence, and life-threatening events. Our study demonstrates the interaction of the interpersonal-psychological theory and other suicide risk factors in Taiwanese soldiers.