At the age of sixteen (1266) he entered the novitiate of the Dominican Order at the Priory of Santa Maria Novella in Florence,[1] and, upon his profession of religious vows the following year, was sent to the University of Paris to complete his studies.

In 1299 Pope Boniface VIII appointed him Bishop of Spoleto and soon afterwards sent him as Papal Legate to the Kings of France and England, Philip IV and Edward I, with a view to reconciling them, a seemingly hopeless task.

The civil wars that in the 13th and 14th centuries had devastated a great part of Italy, especially Tuscany, Romagna and the March of Treviso, caused the pope again to appoint the new cardinal Apostolic Legate, and to send him to restore peace in those disturbed provinces.

He was well received by the people of Florence, but after many futile efforts to effect a reconciliation between the Guelphs and the Ghibellines he left the city and placed it under interdict.

[4] On 29 June 1312, in the name of Pope Clement V, Albertini crowned Henry of Luxembourg as Holy Roman Emperor at Rome.

[3] He was later the leading judge in the trial that exonerated the Dominican friar, Bernardo da Montepulciano, from the charge of killing Henry by giving him a poisoned host at a Mass.

At Avignon he established a community of nuns[5] similar to those founded by St. Dominic[3] at the Church of San Sisto Vecchio in Rome.