People engage in gambling behaviour for a variety of different reasons, some of which are riskier than others in terms of associations with heavy and problem gambling. Stewart and Zack (Addiction 103:1110-1117, 2008) developed a measure called the Gambling Motives Questionnaire (GMQ) that assesses levels of three distinct gambling motives: enhancement (to increase positive emotions), coping (to decrease negative emotions), and social (to increase affiliation). While this measure has been validated in a community-recruited sample of middle-aged gamblers, the GMQ has yet to be validated in emerging adulthood (ages 18-25 years)—a developmental period associated with increased risk for heavy and problematic gambling. The current project tested the psychometric properties of the GMQ in a community sample of emerging adult gamblers using archival data from the Manitoba Longitudinal Study of Young Adults. Participants (N = 487; 73.9% Caucasian; 52.6% female; mean age 22.23 years) completed the GMQ and questionnaire measures of gambling behaviour and problems. Exploratory factor analysis revealed that a three-factor model adequately fit the data; however, problematic items were identified. A modified 9-item version of the GMQ with the problem items removed fit the data well. Both the original 15-item and the 9-item versions had acceptable subscale alpha reliabilities (αs >.78). While all three subscales (from both the 9-item and 15-item versions) were positively correlated with problem gambling, only enhancement motives emerged as a significant independent predictor when the other motives and gambling behaviours were entered as simultaneous predictors. These results suggest the GMQ is a valid measure for tapping motives in emerging adults, and that high enhancement motives are particularly predictive of gambling problems in this developmental period. Future intervention efforts might specifically target enhancement motives in emerging adults.