Retrospective research shows that close to 90 percent of suicides have a diagnosable psychiatric disorder; however, only a small proportion of individuals with psychopathology take their own lives. This article reviews the empirical literature on psychological vulnerability to completed suicide. A search of the MEDLINE and PsycINFO databases yielded 46 cohort or case-control studies that used standardized or structured assessments of psychological dimensions. Five constructs have been consistently associated with completed suicide: impulsivity/aggression, depression, anxiety, hopelessness, and self-consciousness/social disengagement. Current knowledge of psychological vulnerability to completed suicide could inform social and neurobiological research, and thereby deepen understanding of suicide while potentially bridging these areas of study.