The Treaty of Versailles (French: le Traité de Versailles) was one of the peace treaties at the end of World War I. It ended the state of war between Germany and the Allied Powers. It was signed on 28 June 1919, exactly five years after the assassination of Archduke Franz Ferdinand. The other Central Powers on the German side of World War I were dealt with in separate treaties. Although the armistice, signed on 11 November 1918, ended the actual fighting, it took six months of negotiations at the Paris Peace Conference to conclude the peace treaty. The treaty was registered by the Secretariat of the League of Nations on 21 October 1919, and was printed in The League of Nations Treaty Series.

Of the many provisions in the treaty, one of the most important and controversial required Germany to accept responsibility for causing the war (along with Austria and Hungary, according to the Treaty of Saint-Germain-en-Laye and the Treaty of Trianon, respectively) and, under the terms of articles 231–248 (later known as the War Guilt clauses), to disarm, make substantial territorial concessions and pay heavy reparations to certain countries that had formed the Entente powers. In 1921 the total cost of these reparations was assessed at 132 billion Marks (then $31.4 billion or £6.6 billion, roughly equivalent to US $442 billion or UK £284 billion in 2013), a sum that many economists at the time, notably John Maynard Keynes, deemed to be excessive and counterproductive. The argument by Keynes that the terms were too harsh—a "Carthaginian peace"—convinced many British and American leaders, but left the French unmoved.