Pope Francis, who on Wednesday was elected as the first ever Jesuit pontiff, takes over as the major Roman Catholic religious order faces declining membership and diminishing influence in some parts of the world.
The order, otherwise known as the Society of Jesus, included 36,000 members in 1964 but has seen its numbers decline in recent decades to the current 19,000. The order still boasts on its website being "the largest male religious order in the world".
As the Jesuits' influence has decreased in Europe, Asia with 4,035 members, North America (3,034) and Latin America (2,957) have now become its major bases.
The Jesuits were founded in 1534 by Ignatius de Loyola, a Spaniard who as a soldier suffered a war injury and underwent a spiritual conversion. In the following years they became the vanguard of papal power.
They played a key role in taking Catholicism to the new Spanish colonies in the Americas, as well as to Asia.
They were disbanded by Pope Clement XIV in 1773 under pressure from Spain, France, Portugal and Austria, which felt threatened by their strength as political operators and as educators of intellectual elites.
Pope Pius VII restored them in 1814 as a counter to the anti-clerical influences unleashed in Europe by French emperor Napoleon Bonaparte.
Jesuits take vows of poverty, chastity and obedience and under a fourth vow have a special tie to the papacy -- as each member must swear personal allegiance to the pope.
Although the Jesuits had not until Francis' election provided a pope, some critics claim that the Jesuit superior general rules the Vatican behind the scenes.
The Jesuit leader, currently Father Adolfo Nicolas, has traditionally been known as the "black pope" in reference to the order's sombre garb, as against the "white pope" the actual pontiff.
The Vatican has sanctioned a number of Jesuits over the past few decades for straying from official doctrine, including for their views on non-Christian religions, the human Christ and the defence of society's dispossessed -- the focus of the liberation theology movement that swept Latin America in the 1970s.
Throughout their history, the Jesuits have attached great importance to education, with reputed colleges and universities notably in the United States, and the media -- Vatican spokesman Federico Lombardi is a Jesuit.