1973 enlargement of the European Communities

Part of a series of articles on
UK membership of the European Union (1973–2020)
Accession Treaty of Accession 1972 1972 EC Act 1973 enlargement of the EC
1975 referendum Referendum Act (results)
Treaty amendments Single European Act, 1986 (UK ratification) Maastricht Treaty, 1992 (UK ratification) Treaty of Amsterdam, 1997 (UK ratification) Treaty of Nice, 2001 (UK ratification) Treaty of Lisbon, 2007 (UK ratification) Related: 2011 UK Act on new EU Treaty amendments EU-related British Acts Proposed European Constitution referendum European Union Bill 2004–2005
MEPs for UK constituencies Members 1973–1979 (elected by parliament) Members 1979–1984 (1979 election) Members 1984–1989 (1984 election) Members 1989–1994 (1989 election) Members 1994–1999 (1994 election) Members 1999–2004 (1999 election) Members 2004–2009 (2004 election) Members 2009–2014 (2009 election) Members 2014–2019 (2014 election) Members 2019–2020 (2019 election) Women
Officials and bodies House of Lords EU Committee House of Commons EU Committee Permanent EU Representatives for UK Northern Ireland Executive in Brussels EU Representative in London UK European Commissioners Department for Exiting the European Union
Issues and events Economy The Euro Black Wednesday UK budget rebate Nationality law Euroscepticism in the UK United Kingdom opt-outs from EU legislation Maastricht Rebels Balance of Competences Review
Withdrawal 2015 UK general election 2015–2016 membership renegotiation 2016 EU membership referendum Vote Leave Britain Stronger in Europe Notification of withdrawal 2017 UK general election Brexit negotiations Impact of Brexit Future relationship Withdrawal agreement No-deal Brexit Impact on Irish border Northern Ireland Protocol Parliamentary votes Proposed second referendum 2019 UK general election
EU portal UK portal
v t e

The 1973 enlargement of the European Communities was the first enlargement of the European Communities (EC), now the European Union (EU). Denmark, Ireland and the United Kingdom (UK) acceded to the EC on 1 January 1973. Gibraltar and Greenland also joined the EC as part of the United Kingdom and Denmark respectively, but the Danish Faroe Islands, the other British Overseas Territories and the Crown dependencies of the United Kingdom did not join the EC.

Ireland and Denmark both held referendums in 1972 in May and October respectively, and the United Kingdom held a referendum in 1975, on membership of the EC, all which approved membership of the EC. Norway planned to accede, but this was rejected in a referendum held in September 1972. In 1992 Norway again applied to join, but voters again rejected the proposal in a 1994 referendum.

Greenland later withdrew from the EC on 1 January 1985 after a referendum in 1982. This was followed by the United Kingdom holding a referendum in 2016 on membership which resulted in the United Kingdom voting to leave the EU.