Does gender equality in public meetings improve as women’s numbers grow?Research applying critical mass theory to the exercise of influence in publicdiscussion and decision making reveals a complicated story. Women have madesignificant progress in education, employment, and the attainment of elected office;yet, they continue to lag behind their male counterparts in substantive, symbolic,and authoritative representation. Across political, nonpolitical, and experimentalsettings, women’s participation and influence does not follow necessarily from theirnumerical proportion. We review previous studies of how women’s lower status ismanifested in group interaction, and we argue that research can better identify whenand how numbers matter by attending to the group’s context, institutional features,and informal norms. We describe cutting-edge research designed to explore theeffects of institutional rules and norms on women’s authority. Women’s increasingnumbers in positions of potential influence constitutes a timely, promising, andchallenging agenda for further scholarship.