His father was Sir Vincent Casolani who served as a high ranking government official.

He started his studies at the University of Malta and continued at the Seminario Romano in Rome where he obtained a Doctorate in Divinity.

After 2 years, he entered the Collegio Urbano for further studies in Theology and Oriental languages.

He was consecrated on 24 May the same year by Cardinal Giacomo Filippo Fransoni with the Titular See of Mauricastro at the College of Propaganda Fide in Rome.

[1] The following year Casolani went on a mission to Central Africa, accompanied by some Jesuits.