abbess and mystic. In 1620 she took her vows as a Franciscan nun and in 1627 became abbess of a Franciscan monastery in Agreda, retaining this office, except for a brief period, until her death.

Her virtues and holy life were universally acknowledged, but controversy arose over her mystical writings, her political influence, and her missionary activities. Her best-known work is The Mystical City of God (1670), a life of the Virgin Mary ostensibly based on divine revelations granted to María. It was placed on the Index Librorum Prohibitorum in 1681, but the ban was lifted in 1747; Spanish theologians maintained from the start that most of the opposition arose from a misunderstanding of the Spanish text. Despite the book's evident historical, geographic, and chronological errors, scholars value it as an ascetic and mystical treatise.

In 1643 King Philip IV of Spain visited María, initiating a correspondence that was maintained until her death. Their letters dealt with spiritual and political matters and form a rich source for historians on Philip's reign.

María was noted for her encouragement of missionary activity, especially among the Franciscans. She frequently repeated that God had revealed to her his desire to convert the North American Indians and had assured the missionaries the reward of becoming apostles. Some thought her words fanciful, but many others accepted her assurances of success and took up mission work; among them was Junípero Serra, founder of California missions.