Does low descriptive representation inhibit substantive representation for women in deliberating groups? We address this question and go beyond to ask if the effects of descriptive representation also depend on decision rule. We conducted an experiment on distributive decisions, randomizing the group's gender composition and decision rule, including many groups, and linking individuals’ predeliberation attitudes to their speech and to postdeliberation decisions. Women's descriptive representation does produce substantive representation, but primarily under majority rule—when women are many, they are more likely to voice women's distinctive concerns about children, family, the poor, and the needy, and less likely to voice men's distinctive concerns. Men's references shift similarly with women's numerical status. These effects are associated with group decisions that are more generous to the poor. Unanimous rule protects women in the numerical minority, mitigating some of the negative effects of low descriptive representation. Descriptive representation matters, but in interaction with the decision rule.