Basil (Latin: Congregatio a Sancto Basilio, abbreviation CSB), also called the Basilians, is a Catholic clerical religious congregation of pontifical right for men, with priests, seminarians and lay associates.

In the early 19th century, the Basilians' educational and pastoral work brought them to a variety of locations in Canada and the United States.

Increased growth made it necessary to find a new location, and in 1802 the school moved to Annonay in southern France at the suggestion of Henri Léorat-Picansel, a pastor who had previously been in Saint-Symphorien-de-Mahun.

The newly appointed bishop suggested that if they formed an association and bought the property of a nearby school, Maisonseule, that they would have his support.

This “coincided with a desire for closer religious life already shown by several of the priests teaching in the college.” Around 1820, Abbot Bernardin Fustier purchased the Chateau de Maisonseule.

“To these men he was the very symbol of their determination that this work should not fail.” The schools became known for their range of teaching including humanities, rhetoric, philosophy, mathematics, physics and chemistry.

In the early years, boundaries were somewhat fluid on membership in the association, based on who lived in the community and taught at the schools at any time.

The decrees of 1880 targeted Jesuits but affected all teaching orders including the Basilians, and as a result of the persecution they were forced to close one of their schools in 1881 and one of their houses.

[24] This effort was a large investment, risk and sacrifice as it represented a significant percentage of the total number of available Basilian priests.

In ensuing years, more sacrifices were made in manpower and money to continue the mission foundations in Canada; their work took them to Sandwich in 1856 and Owen Sound in 1863.

[26] On April 30, 2020, the Canadian Supreme Court rejected an appeal from the Basilian Fathers of Toronto to deny a $2.6 million settlement to sex abuse victim Rod MacLeod.

In the 1930s the Basilians began an apostolate serving Spanish-speaking populations in Texas in communities such as Galveston, Houston, Sugar Land, Rosenberg, Wharton, New Gulf, Bay City, Angleton, Freeport and Eagle Lake.

The Basilians are no longer a sponsor, but maintain strong links to both The Aquinas Institute and St. John Fisher University (renamed in 2022).