Qu'est-ce que le Tiers-État? (transl. What Is the Third Estate?) is an influential political pamphlet published in January 1789, shortly before the outbreak of the French Revolution, by the French writer and clergyman Abbé Emmanuel Joseph Sieyès (1748–1836). Written during the Assembly of Notables between 6 November and 12 December 1788, it was sent to the printer by 27 December 1788 for publication in the early days of 1789. There were eventually four editions of the text; initially published anonymously as a 127 page pamphlet, Sieyès revealed himself as the author after its third edition in May 1789.
The pamphlet was Sieyès' reply to finance minister Jacques Necker's invitation for writers to state how they thought the Estates-General should be organised. It was one of the most influential pamphlets of the early revolution: some 300,000 copies were printed, reaching around one million readers, establishing Sieyès as one of the principal leaders of the Estates-General upon its opening in May.