We used administrative data to examine predictors of medically documented suicide ideation (SI) among Regular Army soldiers from 2006 through 2009 (N=10,466 ideators, 124,959 control person-months). Enlisted ideators (97.8% of all cases) were more likely than controls to be female, younger, older when entering service, less educated, never or previously deployed, and have a recent mental health diagnosis. Officer ideators were more likely than controls to be female, younger, younger when entering service, never married, and have a recent mental health diagnosis. Risk among enlisted soldiers peaked in the second month of service and declined steadily, whereas risk among officers remained relatively stable over time. Risk of SI is highest among enlisted soldiers early in Army service, females, and those with a recent mental health diagnosis.