The Priestly Fraternity of Saint Peter (Latin: Fraternitas Sacerdotalis Sancti Petri; FSSP) is a traditionalist Catholic society of apostolic life for priests and seminarians. It is in communion with the Holy See. It was founded in 1988 by 12 former members of the Society of Saint Pius X (SSPX) who left following the Écône consecrations, which resulted in the SSPX bishops being excommunicated by the Holy See.

Headquartered in Switzerland, the society maintains two international seminaries: the International Seminary of St. Peter in Wigratzbad-Opfenbach, Bavaria, Germany, and Our Lady of Guadalupe Seminary in Denton, Nebraska, United States. The society is officially recognized by the Holy See and has 368 priests who celebrate the Tridentine Mass in 147 dioceses worldwide.

The fraternity’s pontifical right status means that it has been established by the Pope and is answerable only to him in terms of its operation (through the Dicastery for Institutes of Consecrated Life and Societies of Apostolic Life; prior to January 17, 2019, through the Pontifical Commission Ecclesia Dei), rather than to local bishops. A local bishop continues to oversee the fraternity’s work within his diocese. In this sense, its organizational and administrative reporting status is similar to that of religious orders of pontifical right.

On 28 September 2024, the Dicastery for Institutes of Consecrated Life and Societies of Apostolic Life informed the FSSP that it had opened an apostolic visitation. According to the Fraternity, this is intended to “enable the Dicastery to know who we are, how we are doing and how we live, so as to provide us with any help we may need.”

As of November 2023, the fraternity included 569 members: 368 priests, 22 deacons, and 179 non-deacon seminarians in 146 dioceses spread among Australia, Austria, Benin, Canada, Colombia, Czech Republic, France, Germany, Great Britain, Ireland, Italy, Mexico, Nigeria, New Zealand, Poland, Portugal, Switzerland, the United States, and Vietnam. The fraternity’s membership comprises 35 nationalities, with an average age of 39. As of 2023, the lay Confraternity of Saint Peter had 9,546 members enrolled, who spiritually support the fraternity’s charism.