May Eljeribi, the 46-year-old manager of a private research firm, was elected Sunday to replace Ahmed Nejib Chebbi, who resigned as general secretary of the Progressive Democratic Party after 23 years in the post.
The first woman to lead a political party in North Africa's Maghreb was Louisa Hanoun of the Algerian Workers' Party.
"This is another opportunity for women in Tunisia to fight, not only by working in associations and unions but by taking part in political activity in an important opposition party," Eljeribi told Reuters.
She said her party would now call for an amnesty for political prisoners and for constitutional reform to give Tunisians more freedom of speech and association.
Tunisia is viewed abroad as having some of the most progressive policies in the Arab world on gender equality, but critics accuse the government of suppressing democracy, imprisoning opponents and hindering free speech.
A report released under U.N. auspices this month said that, while women have been appointed as ministers in most Arab countries, they were often only "window dressing for ruling regimes."
The Arab Human Development Report called on the Arab world to adopt affirmative action policies to expand women's participation in all fields of activity in order to overcome rampant discrimination.