Development of interpersonal relationships is a fundamental human motivation, and behaviors facilitating social bonding are prized. Some individuals experience enhanced reward from alcohol in social contexts and may be at heightened risk for developing and maintaining problematic drinking. There has been little systematic research conducted in group settings, though, and no prior studies have tried to link genetic variation to alcohol’s socially reinforcing effects. This research investigated whether the rewarding effects of alcohol in a group setting are associated with genetic variation implicated in the development of alcohol use disorders. Specifically, this study tested the moderating influence of genes encoding the dopamine D2 and D4 receptors, the serotonin transporter, and the alpha receptor for gamma-aminobutryic acid (GABAA) on the effects of alcohol on social bonding. Social drinkers (N=427; males=50.12%) were assembled into three-person unacquainted groups, and given a moderate dose of alcohol, placebo, or a non-alcohol (control) beverage, which they consumed over 36-min. To assess social bonding, participants completed the Perceived Group Reinforcement Scale immediately after the group drinking period. In addition, their social interaction was video-recorded, and the duration of facial behaviors was systematically coded using the Facial Action Coding System. After applying the Bonferroni correction to control for false positives in multiple genotype comparisons, there was one significant gene x environment interaction. Results showed that carriers of at least one copy of the 7-repeat allele of the DRD4 VNTR reported higher perceived social bonding in the alcohol, relative to placebo or control conditions, whereas alcohol did not affect ratings of 7-absent allele carriers. Findings indicate that carriers of the 7-repeat allele were especially sensitive to alcohol’s effects on social bonding. These data converge with other recent gene-environment interaction findings implicating the DRD4 polymorphism in the development of alcohol use disorders, and results suggest a specific pathway by which social factors may increase risk for problematic drinking among 7-repeat carriers.