Reviving the practice of women’s zimun was one of the first innovations of Orthodox feminism. However, according to most, there was no real innovation involved; it was a normative practice that had fallen into disuse.
The Talmud rules that any three people who have eaten a meal together must say Grace together: one issues a request, zimun, to the others to bless God (when one says the words rabbotai/ chaverotai nevarech). This obligation falls equally on a group of three men or three women.
Yet, most women do not say Grace together in a zimun if they have eaten together. This is a case of social norms overriding a clear-cut teaching. The medieval Tosafists say that women do not form a zimun because they do not understand Hebrew. Today, women generally understand as much or little Hebrew as men. Some leading halachic authorities of the last generation affirmed that where three women ate together with fewer than three men, one of the women should lead the zimun, and the others present, including the men, should respond.