Holy See–United States relations: The United States and Holy See (Vatican City) re-establish full diplomatic relations after almost 117 years, overturning the United States Congress's 1867 ban on public funding for such a diplomatic envoy.

The current Ambassador to the Holy See is the ad interim Chargé d'Affaires Laura Hochla, who replaced Joe Donnelly, on July 8, 2024. The Holy See is represented by its apostolic nuncio, Cardinal Christophe Pierre, who assumed office on April 12, 2016. The U.S. Embassy to the Holy See is located in Rome, in the Villa Domiziana. The Nunciature to the United States is located in Washington, D.C., at 3339 Massachusetts Avenue, N.W.

The Holy See, also called the See of Rome, the Petrine See or the Apostolic See, is the central governing body of the Catholic Church and Vatican City. It encompasses the office of the pope as the bishop of the apostolic episcopal see of Rome, and serves as the spiritual and administrative authority of the worldwide Catholic Church and Vatican City. Under international law, the Holy See holds the status of a sovereign juridical entity.

Vatican City, officially the Vatican City State, often improperly shortened as the Vatican, is a landlocked sovereign state and city-state. It is an enclave within Rome, seat of the Catholic Church, and serves as the administrative centre of the Catholic Church. It became independent from the Kingdom of Italy in 1929 with the Lateran Treaty. Vatican City is governed by the See of Rome, commonly known as the Holy See, itself a sovereign entity under international law, which maintains its temporal power, governance, diplomacy, and spiritual independence. Vatican is also used as a metonym for the Holy See, which is the central governing body of the Catholic Church and Vatican City, comprising the pope and the Roman Curia.

The United States Congress is the legislative branch of the federal government of the United States. It is a bicameral legislature, including a lower body, the U.S. House of Representatives, and an upper body, the U.S. Senate. They both meet in the United States Capitol in Washington, D.C.