U.S. military accession mental health screening includes cognitive testing and questions regarding the applicants' past mental health history. This process relies on applicants' knowledge of and willingness to disclose symptoms and conditions. Applicants have a strong incentive to appear qualified, which has resulted in a long history of frequent mental health conditions presenting during recruit training. Objective: To assess the predictive value of a preenlistment noncognitive temperament test score for risk of mental disorders and attrition in the first year of service. Methods: A retrospective cohort study was conducted on non-high school diploma U.S. Army active duty recruits who took the Assessment of Individual Motivation (AIM). Multivariate logistic regression models were used to determine associations between AIM score quintiles, mental disorders, and attrition. Results: AIM scorers in the lowest quintile were at increased risk for a mental disorder (OR, 1.44; 95% CI, 1.35-1.53) and of discharge (OR, 1.65; 95% CI, 1.44-1.68) compared to AIM scorers in the highest quintile, with significant linear trends for decreased risk with increasing AIM score. Conclusions: AIM offers the potential to improve screening of military applicants and reduce mental disorders and attrition in new recruits beyond the current process.