This study aimed at investigating whether all-women and all-men groups differed in their hierarchical organization and stability of their rank orders across time. One hundred and sixteen European, middle-class, noncollege women and men (average age: 38) participated in small-group discussions twice within a week with the same group members. Speaking time served as the behavioral dominance indicator on which group hierarchies were based. Additionally, group members rank ordered each other on dominance after each interaction. In the first session, all-men groups were more hierarchically structured than all-women groups. During each session, all-women and all-men groups showed a similar significant increase in hierarchical structuring. For both women and men, rank orders remained stable during interactions and from the first to the second session. Results are discussed in terms of three theoretical models describing dominance hierarchies.