He studied at the Roman College and in 1640 graduated from the Sapienza with a doctorate in civil and ecclesiastical law, commencing a career as a consistorial lawyer.

[5] So it was that Astalli was elevated to Cardinal on 19 September 1650 by the Pope, who simultaneously adopted him into the Pamphili family (as Camillo Astalli-Pamphili) and appointed him Cardinal-Nephew.

[5] The unexpected generosity of the pope, however, put him against the Pamphilj family and especially Donna Olimpia, so much so that, aided by a series of bad policy choices, as well as a certain inability to handle the Roman Curia, he soon fell out of favor at the papal Court.

[4] In February 1654, with little warning, Pope Innocent stripped Astalli of his titles for allegedly revealing the secrets of state to Spain (plans to invade the Kingdom of Naples).

[5] Nonetheless, when Innocent X died, Astalli was still a Cardinal and participated in the papal conclave of 1655[6] which elected Pope Alexander VII.

[2] On instructions of Philip IV, on 14 July 1661 he was elected during the papacy of Pope Alexander VII as Archbishop (personal title) of Catania.