In 1545, when the Council of Trent was opened, Charles V sent Carranza and another Dominican, Domingo de Soto, as imperial theologians, to the council, and by June, 1545, Carranza was in Trent. During the first period of the council (1545–47) he took an active part in the discussions of the theologians in the congregations, expressed opinions concerning the various matters appointed for discussion, the sacraments in general, Baptism, the Eucharist, and the Sacrifice of the Mass, and preached at Divine service, 14 March, before the assembled council. He also showed great zeal in the conferences concerning the reform of church discipline.