The Society of Jesus, (Societas Iesu, S.J. and S.I. or SJ, SI ) is a Christian religious order of the Roman Catholic Church in service to the universal Church, whose members are called Jesuits, Soldiers of Christ, and Foot soldiers of the Pope, because the founder, Saint Ignatius of Loyola, was a knight before becoming a priest.

Jesuits are the largest male religious order of the Roman Catholic Church with 19,216 members (13,491 priests, 3,049 scholastic students, 1,810 brothers and 866 novices) as of January 2007, (the Franciscan family of first orders OFMs, Capuchins, and Conventuals has some 30,899 members [20,786 priests]). The average age of the Jesuits in 2007 is 57.3 : 63.4 for priests, 29.8 for scholastics and 65.5 for Brothers .

Jesuit priests and brothers are engaged in ministries in 112 nations on six continents. No work, if it has an evangelical perspective, is closed to them, but they are best known in the fields of education (schools, colleges, universities, seminaries, theological faculties), intellectual research, and cultural pursuits. They are also known in missionary work and direct evangelization, social justice and human rights activities, interreligious dialogue, and other 'frontier' ministry.

The Society of Jesus is consecrated under the patronage of Madonna Della Strada, a title of the Blessed Virgin Mary, and it is led by a Superior General, currently Adolfo Nicolás. The headquarters of the Society, called General Curia, is in Rome. The history curia of St Ignatius is now part of the Collegio del Gesù attached to the Church of the Gesù, the Jesuit Mother Church.