The Order of St. John was created before Jerusalem was conquered by the armies of the First Crusade in 1099. This monastic community devoted to St. John the Baptist ran a hospice or infirmary to assist the pilgrims in the Holy Land.

Originally linked to the Benedictines, under the Blessed Gérard the community became an independent Order. With the Bull of February 15, 1113 addressed to Gérard, Pope Paschal II approved the foundation of the Hospital of St. John, placed it under the protection of the Holy See and granted it the right to freely elect its chiefs, Gérard's successors, without any interference by any other religious or secular authority. By virtue of that Bull and of later Papal documents, the Hospital became an Order not subject to the Church.

The political scenario that followed the foundation of the United Kingdom of Jerusalem by the Crusaders forced the Order, guided by its second Superior Brother Raymond du Puy (the first to call himself Master) to undertake the military defense of the pilgrims and of the Christian territories that the Crusaders had won over the Muslims. It was then that the Order of the Hospital of St. John acquired the status of a chivalry order: its Knights were at the same time religious men bound to keep the three monastic vows of Poverty, Chastity and Obedience. So the Order became what was called a persona mixta, i.e. religious and military together.

Brother Raymond du Puy introduced the first known Rule and adopted the eight-pointed cross that is still the symbol of the Order (the Maltese Cross).

While busy addressing the first of its two missions, the aid to the poor (obsequium pauperum), the Order also pursued with success its second mission, the defense of Christendom (tuitio fidei). Nevertheless, in 1291 St. John of Acre, the last Christian bulwark in the Holy Land, was lost, and the Order settled in Cyprus.

The Order later governed the island of Rhodes from 1308 to 1522 and the Maltese islands from 1530 to 1798. From the very beginning, its independence from other countries granted by Papal documents, and its universally recognized right to maintain and employ armed forces represented the grounds for the international sovereignty of the Order.

The Order was ruled by the Grand Master and the Council, minted its own coins and had diplomatic relationships with other countries. The Grand Master was the Prince of Rhodes and later became Prince of Malta.

In 1607 and then again in 1620, the Grand Master also acquired the title of Prince of the Holy Roman Empire and in 1630 a rank equivalent to the dignity of Cardinal of the Holy Roman Church, bearing the appellation of Eminence.

When Malta was lost to Napoleon, the Order settled temporarily in Messina, Catania, Ferrara and then in Rome, where it owns, in regime of extraterritoriality, the "Palazzo di Malta" in Via Condotti 68 and the Villa on the Aventine.

After 1805 the Order was ruled by Lieutenants, but in 1879 Pope Leo XIII restored the office of Grand Master and the related cardinal's honors, and, later on, Art. 38 of the Royal Decree no. 651 of June 7, 1941 recognized to the Grand Master the title of "Most Eminent Highness". The original mission of hospital assistance has become the prominent purpose of the Order. The medical aid and charity activities, already carried out on a large scale during Word War I, were extended during World War II under the direction of the Grand Master Brother Ludovico Chigi della Rovere Albani and increased even more under the direction of the Grand Master Brother Angelo de Mojana di Cologna (1962-1988) whose successor today is the current Prince and Grand Master Brother Andrew Bertie.

The Order has always been recognized by the community of nations ad a sovereign and independent authority. Today the Order has diplomatic relationships at Embassy level with 83 nations, including the Italian Republic.

The Order has also official relationships at Ambassador level with the Russian Federation and is credited by Representatives or Delegates to Belgium, France, Luxembourg, Principality of Monaco, Germany, Switzerland and to the Council of Europe and the Commission of the European Union.

Since 1994 the Order has been admitted as permanent Observer with the United Nations and, as such, it has Permanent Delegations at the International Organizations in New York, Geneva, Paris, Rome and Vienna.

Being a sovereign entity, the Order has its own original laws, called Order Rules, providing for the usual separation of three powers.

The legislative power is vested with the Chapter General, that has also the power to amend the Constitutional Charter and the Order Code - the basic laws of the Order.

The executive power is vested with the Sovereign Council, chaired by the Gran Master and composed of Knights elected by the Chapter General. The Council is the governing authority and may legislate on the matters not ruled by the Constitutional Charter and the Code. The Sovereign Council creates the public organizations of the Order that pursue its institutional missions, by approving the relevant by-laws.

ACISMOM, the association in charge of managing The St. Johon the Baptist Hospital, is a public organization of the Order.

The judiciary power is vested with the Courts of first resort and of appeal, composed of judges elected by the Sovereign Council among Order members having legal expertise.