Objective We examined early first deployment and subsequent suicide attempt among U.S. Army soldiers. Method Using 2004–2009 administrative data and person-month records of first-term, Regular Army, enlisted soldiers with one deployment (89.2% male), we identified 1,704 soldiers with a documented suicide attempt during or after first deployment and an equal-probability control sample (n = 25,861 person-months). Results Logistic regression analyses indicated soldiers deployed within the first 12 months of service were more likely than later deployers to attempt suicide (OR = 1.7 [95% CI = 1.5–1.8]). Adjusting for sociodemographic characteristics, service-related characteristics, and previous mental health diagnosis slightly attenuated this association (OR = 1.6 [95% CI = 1.5–1.8]). Results were not modified by gender, deployment status, military occupation, or mental health diagnosis. The population-attributable risk proportion for deploying within the first 12 months of service was 17.8%. Linear spline models indicated similar risk patterns over time for early and later deployers, peaking at month 9 during deployment and month 5 postdeployment; however, monthly suicide attempt rates were consistently higher for early deployers. Conclusions Enlisted soldiers deployed within the first 12 months of service have elevated risk of suicide attempt during and after first deployment. Improved understanding of why early deployment increases risk can inform the development of policies and intervention programs.