Born as Rinaldo di Jenne in Jenne[1] (now in the Province of Rome), he was, on his mother's side, a member of the family de' Conti di Segni, the counts of Segni, like Pope Innocent III and Pope Gregory IX. His uncle Gregory IX made him cardinal deacon and Protector of the Order of Franciscans in 1227, Camerlengo of the Holy Roman Church from 1227 until 1231 and Bishop of Ostia in 1231 (or 1232). He became Dean of the Sacred College of Cardinals in 1244 (or 1240).