Objective: Although women make up one third of Alcoholics Anonymous (AA) membership, research on gender and AA has been limited. Findings in the literature are mixed, with few empirical investigations of factors that may moderate any gender differences found. AA is highly interpersonal, and research has found that women are more extroverted than men. The current study explores the impact of AA on sobriety, gender differences in the relationship between AA and sobriety, and whether extroversion can inform our understanding of gender differences. Method: A sample of 276 alcohol-dependent adults (180 men, 96 women) was recruited from four sites and followed prospectively for 2.5-3 years. Participants completed the Timeline Followback interview. AA membership was assessed by an item from the Alcoholics Anonymous Involvement scale. Multiple logistic regression analyses were conducted to determine whether gender, extroversion, AA membership, and their interaction would predict sobriety status at follow-up. Results: AA membership significantly increased the odds of achieving a year of sobriety, and this relationship was stronger for women than men (odds ratio [OR] = 4.42, 95% CI [1.14, 17.18]). There were no main or interactive effects of extroversion on sobriety. Conclusions: AA was founded by men, and early in its history it was exclusively attended by men. Some have criticized AA for women because of its emphasis on "powerlessness." Despite its historical beginnings and such debate, this study joins others in finding evidence that women fare better in AA than do men. In this sample, extroversion did not moderate the association between gender and sobriety. Further research is needed on gender differences in AA and its explanatory factors.