Sixtus I (Greek Xystos, 'polished') succeeded Alexander I around AD 115. The Liber Pontificalis attributes to him three significant liturgical-disciplinary decisions: that only consecrated ministers might handle the sacred liturgical vessels of the altar; that bishops returning from Rome to their dioceses must carry an apostolic letter from the pope as testimony of their visit; and that the people should sing the Sanctus (Trisagion) together with the priest at the Eucharist (a chant taken from Isaiah 6:3 — 'Holy, holy, holy, Lord God of hosts') — the first formal liturgical institution of the Sanctus in the Roman Mass.
He governed the Roman community for some ten years. Tradition holds that he was martyred during the reign of Hadrian. His relics were translated from the Roman catacombs to the small Latin town of Alatri in 1132, where they have remained venerated ever since.