Pope Celestine II died on 8 March 1144 at Rome, after pontificate of only five months. The election of his successor took place in the shadow of this municipal revolution, which opposed the secular rule of the Pope. Celestine II was unable to recover the full control over the city of Rome; in addition he had to face also the demands of the king Roger II of Sicily. This problem also remained unresolved on his death, because he had refused to confirm the privileges granted to Roger by his predecessor Innocent II.
The cardinals present at Rome elected Cardinal Gerardo Caccianemici, priest of the titulus of S. Croce in Gerusalemme and former canon regular of S. Frediano di Lucca. The details concerning the place of the election or the exact date of electoral proceedeings are not registered. Since the elect was chancellor of the Holy See and close collaborator of both Innocent II and Celestine II, it may be assumed that the cardinals wanted to continue their policy, friendly towards the Empire and hostile towards the king Roger. The elect took the name of Lucius II and received episcopal consecration on 12 March 1144.
There were probably 39 cardinals in the Sacred College of Cardinals in March 1144. Basing on the examination of the subscribtions of the papal bulls in 1144 and the available data about the external missions of the cardinals it is possible to establish that no more than 36 cardinals participated in the election:
^Reconstruction is based on Brixius, p. 22 note 4 with the following corrections: bishop Rodolfo of Orte has been excluded because he was not a cardinal at that time (Zenker, p. 52-53). Additionally, Brixius indicates that also Bernardo da Pisa, future Pope Eugene III, belonged to the College of Cardinals (similarly Zenker, pp. 184–187), but see M. Horn: Studien zur Geschichte Papst Eugens III.(1145-1153), Peter Lang Verlag 1992, pp. 42–45.