Belonging to a family of ancient nobility, he dedicated himself to an ecclesiastical career after the death of his wife, having already had a son Filippo who joined the
Franciscan Order. In 1216 Stefano was appointed cardinal deacon of
Sant'Adriano al Foro by Pope Innocent III, of whom he was a nephew. In 1228 he was translated to the title of cardinal priest of
Santa Maria in Trastevere and in 1231 he was appointed Archpriest of the
Vatican Basilica. He also received
prebends of Lyme & Halstock (Salisbury), Lincoln, and York. After Pope
Innocent IV had fled Rome for
Lyon during his confrontation with Emperor
Frederick II, Conti became
Cardinal Vicar of Rome from 1244 to 1251. In 1245 he became the
Protopriest of the College of Cardinals. At the request of the pope, he reduced the number of canonics from 36 to 25 and reformed the chapter of the
Lateran Basilica. Conti served as
papal legate in the
Kingdom of Sicily where he pronounced papal deposition of Frederick. He then served as governor of the provinces of
Sabina and
Campagna e Marittima of the
Papal States. He built and decorated the chapel of St. Sylvester at the church of
Santi Quattro Coronati. He died in Naples on 8 December 1254, the last of the cardinals of Innocent III, and was buried in the city's
cathedral. ==Conclaves==