Pope Pius XII in 1948, established a commission for liturgical reform led by Annibale Bugnini, who would later become one of the chief architects of the liturgical reforms of Paul VI. On 9 February 1951, Pius XII published the decree Dominicae Resurrectionis which authorized, in 1951 the introduction of revised texts for Easter Vigil. The regulations were initially deemed "ad experimentum" for one year, but in 1952 they were extended for another three years. After positive reports from the world's bishops, these changes were made universally obligatory on 16 November 1955, with the decree Maxima Redemptionis Nostrae Mysteria, which took effect on 25 March 1956 (Palm Sunday), which made substantial changes to Palm Sunday, Holy Thursday, Good Friday, and the Easter Vigil. Pius XII also removed from the Vigil of Pentecost, the series of six Old Testament readings, with their accompanying Tracts and Collects, but these continued to be printed until 1962.
Pope Pius XII in 1948, established a commission for liturgical reform led by Annibale Bugnini, who would later become one of the chief architects of the liturgical reforms of Paul VI. On 9 February 1951, Pius XII published the decree Dominicae Resurrectionis which authorized, in 1951 the introduction of revised texts for Easter Vigil. The regulations were initially deemed "ad experimentum" for one year, but in 1952 they were extended for another three years. After positive reports from the world's bishops, these changes were made universally obligatory on 16 November 1955, with the decree Maxima Redemptionis Nostrae Mysteria, which took effect on 25 March 1956 (Palm Sunday) which made substantial changes to Palm Sunday, Holy Thursday, Good Friday, and the Easter Vigil. Pius XII also removed from the Vigil of Pentecost, the series of six Old Testament readings, with their accompanying Tracts and Collects, but these continued to be printed until 1962.