1735–1815, American Roman Catholic churchman, b. Maryland. He studied as a child with Jesuits at Bohemia, Md., and later at Saint-Omer in Flanders, since Catholic secondary education was not allowed in Maryland. He joined the Jesuits in 1753, studied at Liège, and was ordained in 1769. After the suppression of the Jesuits he returned to America and traveled about, ministering to scattered Catholics. He maintained a private chapel, for Catholic churches were forbidden by law. He ardently supported the American Revolution and accompanied Benjamin Franklin (his close friend) on an unsuccessful mission to Quebec (1776) to persuade the Canadians to join the Revolutionary cause. Believing that American Roman Catholics should be free of supervision by the vicar apostolic of London, he led in petitioning Rome for the appointment of a priest in America with some episcopal powers. In 1784, Father Carroll was made superior of the missions in the United States. In the same year he published a controversial pamphlet, An Address to the Roman Catholics of the United States of America, to combat a paper impugning the loyalty of Catholics. In 1790 he was consecrated bishop of Baltimore. He welcomed the Sulpicians, who opened a seminary at Baltimore, and he founded Georgetown Univ. Carroll fostered many communities and founded schools throughout his diocese. In 1808 he became archbishop, with suffragans at Boston, New York City, Philadelphia, and Bardstown, Ky. His last years were somewhat clouded by disputes with Catholic communities in Pennsylvania, Virginia, Georgia, South Carolina, and Maryland over his episcopal jurisdiction.
- J. G. Shea (1888), P. K. Guilday (1922), and A. M. Melville (1955).