 Named assistant librarian of the Vatican Library in 1919 and Monsignor in 1921, Tisserant became Pro-Prefect of the Vatican Library on 15 November 1930 and was named a protonotary apostolic on 13 January 1936.In the consistory of 15 June 1936, Tisserant was created Cardinal Deacon by Pope Pius XI, assigned as his titular church the Basilica of Santi Vito, Modesto e Crescenzia.He was raised to the rank of Cardinal Priest soon afterwards, retaining the same title.