Mater Ecclesiae (Mother of the Church) Abbey (Italian: Abbazia Mater Ecclesiae) is an Italian Benedictine territorial abbey of nuns founded in 1973. The abbey is located on Lake Orta in northern Italy, considered one of the most scenic sites in the country.

By 1973 the community of Benedictine nuns of the Abbey of Viboldone, near Milan , which had been established in 1941 to care for the needy children of wartime Italy, had grown to the point that they considered opening a new foundation. They were offered the facilities of the former bishop's residence on San Giulio Island for this, which they accepted.

Six nuns were chosen to undertake this enterprise, under the direction of Mother Anna Maria Cànopi, O.S.B., who was appointed as the first prioress of the new monastery. Within fifteen years the small community had expanded so much that new quarters were needed.