Den självständiga staten ökade suveräniteten genom Westminsterstatuten 1931 och abdikeringskrisen 1936.[8] En ny konstitution infördes 1937 och förklarade det en suverän stat med namnet Ireland (Éire).[9][10] I Republic of Ireland Act utropades Irland till republik 1949 genom att de återstående plikterna mot monarkin avlägsnades. Irland utträdde därmed ur det brittiska samväldet.[11]
Även om det rankas bland de rikaste länderna i världen idag mätt i BNP,[12] var Irland ett av de fattigaste länderna i Europa medan det var en del av Storbritannien och i decennier efter självständigheten. Ekonomisk protektionism avvecklades i slutet av 1950-talet och Irland gick med i Europeiska ekonomiska gemenskapen 1973.
Ekonomisk liberalism från slutet av 1980-talet resulterade i en snabb ekonomisk expansion, framförallt från 1995 till 2007, då Irland blev känt som den keltiska tigern. En aldrig tidigare skådad finanskris i början av 2008 avslutade denna tid av snabb ekonomisk tillväxt.[13][14]
^Statutory Rules & Orders published by authority, 1921 (No. 533); Ytterligare källa för 3 maj 1921-datumet: Jackson, Alvin (2004) (på engelska). Home Rule – An Irish History. Oxford University Press. sid. 198
^DW Hollis, 2001, The History of Ireland, Greenwood: Connecticut Michael J. Kennedy, 2000, Division and consensus: the politics of cross-border relations in Ireland, 1925–1969, Institute of Public Administration: Dublin
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"In April 1936 de Valera had announced that he was preparing to draft a new constitution to replace that of 1922. Drafting was in progress when the abdication of King Edward VIII in December 1936 gave de Valera the opportunity to make further constitutional changes and introduce the External Relations Bill. In London, the cabinet's Irish Situation Committee had been told by [Malcolm] MacDonald in November 1936 to expect such legislation in the near future, so its introduction was not a shock to the British. Even so, de Valera was concerned about the possible British reaction, and he was able to use the abdication crisis to implement a further revision of the Treaty, safe in the knowledge that British politicians had other matters on their minds."
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^Bill Kissane, 2007, Éamon de Valéra and the Survival of Democracy in Inter-War Ireland in Journal of Contemporary History, Vol. 42, Nr. 2, 213–226
^T Garvin, 1922: the birth of Irish democracy, Gill & Macmillan: Dublin, 2005 Cottrell, Peter (2008) (på engelska). The Irish Civil War 1922–23. Osprey Publishing. sid. 85. ISBN 9781846032707. ”Irish voters approved a new constitution, Bunreacht na hÉireann, in 1937 renaming the country Éire or simply Ireland.” Dr. Darius Whelan (juni 2005). ”Guide to Irish Law” (på engelska). http://www.nyulawglobal.org/globalex/Ireland.htm. Läst 11 september 2009. ”This Constitution, which remains in force today, renamed the State Ireland (Article 4) and established four main institutions – the President, the Oireachtas (Parliament), the Government and the Courts.” John T. Koch, Celtic culture: a historical encyclopedia, ABC-CLIO: Santa Barbara, 2006
^Kondō, Atsushi (2001) (på engelska). Citizenship in a Global World: Comparing Citizenship Rights for Aliens. Hampshire: Palgrave. sid. 120. ISBN 0-333-80265-9. ”Ireland reluctantly remained a member of the Commonwealth s Irish citizens remained British Subjects. However, Irish representatives stopped attending Commonwealth meetings in 1937 and Ireland adopted a position of neutrality in World War II. Ireland became a Republic in 1949 and formally left the Commonwealth.”