INTRODUCTION: U.S. military personnel have a high prevalence of alcohol misuse, which can adversely affect force readiness. The objective of this study was to identify pre-service predictors of new-onset alcohol misuse among male Marines. METHODS: Data for this retrospective cohort study were collected from male U.S. Marines who completed a baseline survey at the beginning of military training from 2013 to 2021 and a standard health assessment 12-36 months later (n=28,337). An Alcohol Use Disorders Identification Test-Consumption (AUDIT-C) score ≥4 indicated alcohol misuse. Independent predictors of alcohol misuse were evaluated using a modified Poisson regression to calculate adjusted risk ratios (aRRs) and 95% CIs. Analyses were conducted between 2022 and 2024. RESULTS: The incidence of new-onset alcohol misuse was 16.3% (n=4,632). In the final multivariable model, the strongest predictor of new-onset alcohol misuse was turning 21 years old during the study period (aRR=3.70
95% CI=3.40, 4.03). Pre-service tobacco use (aRR=1.32
95% CI=1.22, 1.43) and some pre-service alcohol use (AUDIT-C score 1-3: aRR=1.32
95% CI=1.24, 1.40) were also associated with new-onset alcohol misuse. CONCLUSIONS: Multiple pre-service predictors were associated with new-onset alcohol misuse in male Marines. These findings should be considered when screening for alcohol misuse and developing clinical interventions to mitigate adverse impacts of alcohol misuse in the military.