The Diplomatic Society of Saint Gabriel (DSSG) was organized as "Diplomatic Order of the Knights of Saint Gabriel" on 29 September 1996 in the United Nations Headquarters, New York City. The Society was founded a a professional fellowship among diplomats, consuls, international civil servants and other international relations professionals in line with the principles and ethos of the International Alliance of Catholic Knights (IACK). Its founding members hailed from Colombia, Mozambique, the Philippines and the United States.

The DSSG welcomes Catholic diplomats and international relations professionals from all nations. Diplomats of other faiths are welcome as honorary members. Gentleman members are known as Knights of Saint Gabriel, while lady members are organized in a parallel manner as Dames of St. Gabriel. The youth wing of the society are composed of Squires of St. Gabriel.

The Society, a fraternal organization, promotes the advancement of the diplomatic profession, spiritual development and brotherly fellowship. It also seeks to be a catalyst for furthering the humanitarian work of the international community, of the Church, the United Nations, states and civil society.