Ieuan Wyn Jones in the context of Ynys Môn (National Assembly for Wales constituency)

Plaid Cymru (English: /plaɪd ˈkʌmri/ plyde KUM-ree, Welsh: [plaid ˈkəmrɨ]; lit. 'Party of Wales', officially Plaid Cymru – the Party of Wales, and often referred to simply as Plaid) is a centre-left, Welsh nationalist political party in Wales, committed to Welsh independence from the United Kingdom. It campaigns on a platform of social democracy and civic nationalism. The party is a supporter of the European Union and is a member of the European Free Alliance (EFA). The party holds 4 of 32 Welsh seats in the UK House of Commons, 14 of 60 seats in the Senedd, and 200 of 1,234 principal local authority councillors. Plaid was formed in 1925 under the name Plaid Genedlaethol Cymru ('the national party of Wales') and Gwynfor Evans won the first Westminster seat for the party at the 1966 Carmarthen by-election.

In 1999 (in the first devolved Welsh Assembly election), Plaid Cymru gained considerable ground in traditionally Labour heartlands. These breakthroughs were part of the intentional aim to win more seats in the Welsh valleys and North East Wales, which continues to be an ambition today. The party have mostly been in opposition in the Senedd. Although under the leadership of Ieuan Wyn Jones, the party was part of a coalition as a junior partner with Welsh Labour (See: One Wales, Morgan and Jones governments) between 2007 and 2011. Wyn Jones became the deputy First Minister and Minister for the Economy and Transport, other Plaid Cymru Assembly members were also part of the cabinets.

One Wales (Welsh: Cymru'n Un [ˈkəmrɨn ˈɨn]) was the coalition agreement for the National Assembly for Wales between Labour and Plaid Cymru agreed to by Rhodri Morgan, First Minister of Wales and leader of Welsh Labour, and Ieuan Wyn Jones, leader of Plaid Cymru, on 27 June 2007. It was negotiated in the wake of the preceding National Assembly election which resulted in a large Labour plurality, but no majority. Labour and Plaid Cymru approved the document in separate votes on 6 and 7 July, respectively.

The deputy first minister of Wales (Welsh: dirprwy brif weinidog Cymru) is the deputy leader of the Welsh Government. The post was created in October 2000 when Mike German of the Welsh Liberal Democrats was appointed Deputy First Minister as part of a coalition government with Welsh Labour. Since the office was created, the holder has traditionally been the party leader of the junior partner in coalition with Welsh Labour, though this changed in 2024 with the appointment of Labour's Huw Irranca-Davies in the Labour government of Eluned Morgan.

The last holder was Ieuan Wyn Jones of Plaid Cymru who was also the minister for the Economy and Transport. Ieuan Wyn Jones served in the office as part of the One Wales agreement between Plaid Cymru and Welsh Labour between 2007 and 2011.