The Treaty Debates was a series of debates of the Second Dáil sitting in Dublin between the supporters and opponents of the Anglo-Irish Treaty signed on 6 December 1921 between representatives of the Irish Republic and the coalition government of Lloyd George. The Treaty had been negotiated by Irish envoys with plenipotentiary powers and required to be ratified by the Dáil and the British Houses of Parliament. The Treaty was approved on 7 January 1922 by a narrow margin of 64 to 57 (see Anglo-Irish Treaty Dáil vote).
The debates ran from 14 December 1921 to 7 January 1922 but were not publicised until 1972, 'in all their aggression and rawness'. They comprise a vital resource on the psychology of the Irish War of Independence and show the varying ideals that sustained the Sinn Féin deputies. Definitions of their understanding of their mandate in 1918 and 1921, and of the Republic itself, are interspersed with the practicalities of devolving power from London to Dublin. The narrow division led to the outbreak of the Irish Civil War on 28 June 1922.