Suicide has become one of the leading causes of death in the US military in recent years. Understanding the circumstances and factors leading to suicide in military members and identifying appropriate interventions is of high priority for military and civilian leaders. This study prospectively examined and quantified factors associated with risk suicide in a large population of active, Reserve, and National Guard members across all branches of the military during and following service, who were included in the Millennium Cohort Study (N = 151.560).