This volume, edited by the Pontifical Missionary Union, offers the English version of the four main papers presented at the International Congress "Dalla Maximum Illud alla Evangelii Gaudium, Sull'Urgenza della Transformazione Missionaria della Chiesa" (From Maximum Illud to Evangelii Gaudium, On the Missionary Transformation of the Church), organized by the Pontifical Urban University (PUU) in Rome from November 27-29, 2019. The Congress Proceedings were published in 2021, in Italian, in the book with the same title by the Urbaniana University Press (UUP).