Santa Maria in Domnica
Pompili later returned to the Congregation of the Council upon becoming its secretary on 31 January 1908. As secretary, he served as the second-highest official of that dicastery, successively under Cardinals Vincenzo Vannutelli and Casimiro Gennari. Before becoming a bishop, Pompili was created cardinal deacon of Santa Maria in Domnica by Pope Pius X in the consistory of 27 November 1911. Pius X later named him Vicar General of Rome, and thus in charge of the pastoral of the Diocese of Rome, on 7 April 1913.