They consisted of three documents:
Negotiations for the settlement of the Roman Question began in 1926 between the government of Italy and the Holy See, and in 1929 they culminated in the agreements of the three Lateran Accords, signed for King Victor Emmanuel III of Italy by Prime Minister Benito Mussolini and for Pope Pius XI by Cardinal Secretary of State Pietro Gasparri. The agreements were signed in the Lateran Palace, hence the name by which they are known.
The agreements included a political treaty which created the state of the Vatican City and guaranteed full and independent sovereignty to the Holy See. The Pope was pledged to perpetual neutrality in international relations and to abstention from mediation in a controversy unless specifically requested by all parties. The concordat established Catholicism as the religion of Italy. The financial agreement was accepted as settlement of all the claims of the Holy See against Italy arising from the loss of temporal power in 1870.
The sum thereby given to the Holy See was actually less than Italy declared it would pay under the terms of the Law of Guarantees of 1871, by which the Italian government guaranteed to Pope Pius IX and his successors the use of, but not sovereignty over, the Vatican and Lateran Palaces and a yearly income of 3,250,000 lire as indemnity for the loss of sovereignty and territory. The Holy See, on the grounds of the need for clearly manifested independence from any political power in its exercise of spiritual jurisdiction, had refused to accept the settlement offered in 1871, and the Popes thereafter until the signing of the Lateran Treaty considered themselves prisoners in the Vatican, a small, limited area inside Rome.
To commemorate the successful conclusion of the negotiations, Mussolini commissioned the Via della Conciliazione (Road of the Conciliation), which would symbolically link the Vatican City to the heart of Rome.
The Lateran Agreements were incorporated into the Constitution of the Italian Republic in 1947.
In 1984 an agreement was signed, revising the concordat. Among other things, it ended the Church's position as the state-supported religion of Italy.