Hildegard of Bingen, abbess of a twelfth-century Benedictine community on the Rhine, exemplifies the scope some medieval abbesses achieved beyond ordinary monastic administration: she corresponded with popes and emperors, preached publicly with ecclesiastical permission unusual for a woman of her era, and produced theological, medical and musical works of lasting influence, activity her standing as abbess helped make possible within a church otherwise closed to female public authority. Other medieval abbesses, particularly those governing wealthy and well-connected royal or noble foundations, similarly wielded influence well beyond their convent walls through their communities' land holdings, political connections and, in the case of double monasteries such as several English and Frankish houses, direct authority over male religious as well as female.
An abbess is elected by the professed nuns of her own monastery according to the community's constitutions, generally for a fixed term though historically often for life, and her election, like an abbot's, is followed by a blessing conferred by a bishop rather than an ordination. The scope of an abbess's authority has narrowed considerably since the medieval period, as canon law reforms progressively brought women's religious communities under closer and more uniform diocesan and Vatican oversight, ending the more autonomous, occasionally quasi-territorial standing some medieval abbesses had achieved.