Suicide has emerged as a leading cause of death among US military personnel. To assess factors associated with suicide in current and former members of the military, LeardMann and colleagues analyzed linked data from the Millennium Cohort Study—a prospective study that commenced in 2001 and has enrolled 151 560 participants from all branches of the armed services—the National Death Index, and the Department of Defense Medical Mortality Registry. The authors report that 83 suicides occurred between July 2001 and December 2008. Factors associated with an increased risk of suicide included male sex and mental disorders (depression, bipolar disorder, and alcohol-related problems) but not deployment-related variables (combat experience, days deployed, and number of deployments). In an Editorial, Engel discusses the need to address modifiable mental health antecedents of suicide among individuals with a history of military service.