Sisterhood is Global Institute (SIGI), 1984-2000

During the Iranian Revolution, Mahnaz Afkhami met Robin Morgan, an editor, poet, and feminist. Morgan asked her to write a chapter on Iran for Morgan's upcoming book Sisterhood Is Global: An Anthology of the International Women's Movement which would be published in 1984. From this anthology, Morgan, Afkhami and their fellow contributors created the Sisterhood is Global Institute (SIGI), which defined itself as a global women's think tank. 

Afkhami, alongside SIGI, began to introduce more women's work through the Foundation for Iranian Studies (FIS). This included exhibits of women's art, presentations by women scholars and literary figures, the screening of films by women directors, special issues of the FIS journal Iran Nameh dedicated to women's history, and eventually an FIS Women's Center. 

Afkhami worked closely with many other notable feminists during this time, like Bella Abzug, a former United States congresswoman, Marilyn Waring, a New Zealand politician, and Gwendoline Konie, Zambia's ambassador to Germany. During this time, the Center for Women's Global Leadership was created and Afkhami worked closely with its founding executive director, author and activist Charlotte Bunch.

Afkhami would go on to serve as the executive director and president of SIGI. In 1993 the UN held the second World Conference on Human Rights in Vienna, Austria. There, Afkhami was joined by fellow SIGI members Sima Wali, Hilkka Pietila, and Gertrude Mongella, as well as the director of the Women's Division of Human Rights Watch Dorothy Thomas, for a panel entitled "Third World Women and Global Feminism". 

Throughout her tenure with SIGI, Afkhami would use her experiences, from both Iran and Exile, to help push the organization forward to support more women around the globe.