In the Catholic liturgy , the Tridentine Mass is that form of the Eucharistic celebration of the Roman rite promulgated by Pope Pius V in 1570 at the request of the Council of Trent , up to the revision ordered by the Second Vatican Council . It was maintained, with minor modifications, in subsequent editions of the Roman Missal until the one promulgated by John XXIII in 1962.
For four centuries it was the form of the Eucharistic liturgy of most of the Latin Church until the publication of the edition of the Missal promulgated by Pope Paul VI in 1969 following the Second Vatican Council . All the Tridentine editions, while introducing some changes, contained the text of the bull Quo primum tempore with which Pius V promulgated the first edition and were entitled Missale Romanum ex decree Sacrosancti Concilii Tridentini restitutum , while the editions subsequent to 1969 have the title Missale Romanum ex decree Sacrosancti Oecumenici Vatican Councils II instauratum .
The twentieth century saw changes to the Tridentine Mass made in particular by Pope Pius X , Pope Pius XII and Pope John XXIII . The use of the 1962 edition , but not of the previous ones, is still allowed as an " extraordinary form of the Roman rite ", expression that indicates that, if on the one hand it is no longer the ordinary or "normal" form, on the other hand it is not a distinct rite, but only a "different form of the same rite".