Using a full cross-lagged model, this study investigates the extent to which drinking motives predict alcohol use and related consequences, and vice versa. At baseline and 15 months later, 4575 men (mean age = 19.4 years) in Switzerland completed a questionnaire assessing drinking motives, average weekly consumption, risky single-occasion drinking, and alcohol-related consequences. Results indicated that social and enhancement motives more strongly influenced alcohol use over time than the other way round. Coping motives predicted an increase in alcohol-related consequences, and vice versa. Higher social motives predicted an increase in coping motives while higher coping motives predicted a decrease in enhancement motives. These results suggest that social and enhancement motives amplify each other in early adulthood and predict increases in risky drinking. Structural measures aimed at reducing opportunities to engage in heavy drinking are recommended. Additionally, the detection of young adult men vulnerable to maladaptive coping behaviors appears important for alcohol prevention strategies.