The Pope has appointed a woman as an undersecretary to the Synod of Bishops for the first time.
Sister Nathalie Becquart, who is from France, will have voting rights in the body, which advises the pontiff and debates some of the most controversial issues in the Roman Catholic Church.
Ms Becquart has worked with the synod as a consultant since 2019.
The body's secretary-general, Cardinal Mario Grech, said the appointment showed that "a door has opened".
He noted that the decision reflects the Pope's desire "for a greater participation of women in the process of discernment and decision-making in the church".
The BBC's John McManus says the move is not a precursor to ordaining women as priests, although some opponents may regard it as a further step in that direction.
Luis Marín de San Martín, a priest from Spain, was also named as a new undersecretary of the synod.
In recent years, the Synod of Bishops has debated topics of doctrine including the treatment of divorced and married Catholics.
The news comes less than a month after Pope Francis formally changed the law in the Church to allow women to administer communion and serve at the altar, although the decree stressed that ordained priesthood would remain open to men only.
Last year, meanwhile, the pontiff appointed six women to the council which oversees the Vatican's finances.
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