As a feminist and pacifist, she was involved with Portuguese and international pacifist groups, in addition to being a co-founder of the ("Grupo Português de Estudos Feministas"), which was formed in 1907, led by Ana de Castro Osório, Adelaide Cabete, also a doctor with whom Quintino had studied in Lisbon, and Maria Veleda. This organization, which closed in 1908, had the aim of spreading the ideals of female emancipation. Despite its short life it formed the basis for the future development of other, longer-lasting women's movements. Quintino wrote feminist articles in a journal aimed at women, "Jornal das Senhoras", and wrote training material for women, with special attention to children's health. Like most of those who shared her beliefs, she was also a Republican in favour of the overthrow of the monarchy, which took place on 5 October 1910. After the establishment of the First Portuguese Republic, and as a member of the Republican League of Portuguese Women, she argued strongly to change the law to permit divorce.