Many monkeys that are reared without adult influence, with only peers, voluntarily consume alcohol in amounts producing intoxication on a relatively regular basis. Using a cross-over design, eight adolescent, peer-reared rhesus monkeys were allowed unfettered access to an 8.4% ethanol solution and treated with 20 mg/kg/24 h of sertraline during three phases: home-cage, social separation, and reunion with cage-mates. Although there was no immediate effect, sertraline reduced alcohol consumption beginning the second week of home-cage treatment, but only in subjects that consumed large amounts of alcohol. Initially, the social separation stress caused the sertraline-treated subjects’ alcohol consumption rates to return to baseline levels, but when the stress was repeated, alcohol consumption fell below baseline and placebo levels. Sertraline treatment was ineffective in reducing consumption during the stressful period of home-cage reunion, a period characterized by high levels of aggressive behavior. Behaviorally, sertraline reduced aggression and anxiety-like self-directed behaviors. Our findings provide evidence that sertraline may be an effective pharmacological treatment for excessive alcohol consumption and aggression. On the other hand, stress during treatment may reduce sertraline's effectiveness as a treatment for excessive alcohol consumption.