Alcohol abuse disrupts core executive functions, including working memory (WM)--the ability to maintain and manipulate goal-relevant information. When executive functions like WM are weakened, drinking behavior gets out of control and is guided more strongly by automatic impulses. This study investigated whether training WM restores control over drinking behavior. Forty-eight problem drinkers performed WM training tasks or control tasks during 25 sessions over at least 25 days. Before and after training, we measured WM and drinking behavior. Training WM improved WM and reduced alcohol intake for more than 1 month after the training. Further, the indirect effect of training on alcohol use through improved WM was moderated by participants' levels of automatic impulses: Increased WM reduced alcohol consumption in participants with relatively strong automatic preferences for alcohol. These findings are consistent with the theoretical framework and demonstrate that training WM may be an effective strategy to reduce alcohol use by increasing control over automatic impulses to drink alcohol.