ABSTRACT. Objective: Although couples' alcohol use has been associated with intimate partner aggression and poorer marital functioning, few studies have examined the proximal effects of alcohol on couple interactions. The current experimental study examined the effects of alcohol, administered independently to male and female intimate partners, on positive and negative interaction behaviors within a naturalistic confl ict resolution paradigm. Method: Married and cohabiting couples (n = 152) were recruited from the community and each partner randomly assigned to receive either alcohol (target dose: .08 mg/kg) or no alcohol. They engaged in two 15-minute interactions regarding current disagreements in their relationship, one before and one after beverage administration. Videotaped interactions were coded by trained observers using the Rapid Marital Interaction Coding System, and positive and negative interaction behaviors were analyzed using the Actor-Partner Interdependence Model. Results: Participants displayed decreased negativity and increased positivity following alcohol consumption when their partners were sober but no differences in negativity or positivity when their partners also consumed alcohol. There were no gender differences. Although participants with a history of perpetrating intimate partner aggression displayed more negativity, prior aggression did not interact with beverage condition. Conclusions: The immediate effects of alcohol consumption on couple interaction behaviors appeared more positive than negative. Contrary to hypotheses, congruent partner drinking had neither particularly positive nor particularly negative effects. These unique fi ndings represent a rare glimpse into the immediate consequences of alcohol consumption on couple interaction and stand in contrast to its delayed or long-term effects. (J. Stud. Alcohol Drugs, 75, 249-258, 2014)