Hazardous drinking in the armed forces is a significant problem. Alcohol use motivations, known risk factors for problem drinking, have been underexplored in this population. Our study extends knowledge about drinking motives among current and former U.S. service members and provides recommendations on their utility in identifying alcohol-related problems by examining the factor structure of multidimensional drinking motives and their association to alcohol use. Post-9/11 separated service members and current reservists were recruited from 35 Oregon employers to participate in a workplace study of supervisor support. The resulting sample (N = 509; 84% male; mean age = 39) completed a baseline assessment, which included a comprehensive drinking motives assessment. Drinkers comprised 88% of the sample, with a mean Alcohol Use Disorders Identification Test (AUDIT) score of 5.4 (SD = 4.6); 23.9% scored 8 or more. The four-factor structure of the Drinking Motives Questionnaire-Revised, short form (DMQ-R-SF) was affirmed through confirmatory factor analysis. Internal drinking motives related to enhancement (positive) and coping (negative) were most predictive of alcohol use; coping motives were uniquely predictive of alcohol-related problems, when drinking quantity/frequency, as well as psychological distress, were controlled for. Coping motives also mediate the relationship between psychological distress and AUDIT scores. Results thus demonstrated the generalizability of the DMQ-R-SF motives measure for use with separated service members and reservists. Drinking motives, assessed by the DMQ-R-SF, represent reliable and important predictors of drinking and associated problems among service members. Inclusion of motivated drinking questions may enhance screening for alcohol-related problems among current and former service members.