The Order of St. John was founded by St. Gerard as a monastic community in 1048. The Order became well-known by founding a hospital for pilgrims to the Holy Land. By the Bull of 15 February 1113, Pope Paschal II approved the foundation of the hospital and placed it under the protection of the Holy See.

The Knights, the members of the Order, were in fact monks bound by the three monastic vows of Obedience, Chastity and Poverty. They were also obliged to protect the sick and the pilgrims as well as to defend the territories conquered by the crusaders, thus adding a military character to their hospitaller one: the defense of Christian Faith.

When Christian dominance in the Holy Land fell in 1291, the Order temporarily settled in Cyprus, then on the island of Rhodes, and finally on the island of Malta which they had to leave being banned by Napoleon. The Order temporarily resided in Messina, Catania and Ferrara, and then in 1834 they settled definitely in Rome.

The original hospitaller mission became once again the main activity of the Order, growing ever stronger during the last century, most especially because of the contribution of the activities carried out by the Grand Priories and National Associations in many countries around the world where the Order is present.