Plaid Cymru (Welsh pronunciation: [ˈplaɪd ˈkəmrɨ], English: The Party of Wales; often referred to simply as Plaid) is a political party in Wales. It advocates the establishment of an independent Welsh state.

Plaid Cymru was formed in 1925 and won its first seat in 1966. Plaid Cymru by 2012 had 1 of 4 Welsh seats in the European Parliament, 3 of 40 Welsh seats in the Parliament of the United Kingdom, 11 of 60 seats in the National Assembly for Wales, and 206 of 1,264 principal local authority councillors.

Plaid Cymru's goals as set out in its constitution are:

In September 2008, a senior Plaid Cymru assembly member spelled out her party's continuing support for an independent Wales. The Welsh Minister for Rural Affairs, Elin Jones, kicked off Plaid's annual conference by pledging to uphold the goal of making Wales a European Union member state. She told the delegates in Aberystwyth that the party would continue its commitment to independence under the coalition with Labour.

While both the Labour and Liberal parties of the early 20th century had accommodated demands for Welsh home rule, no political party existed for the purpose of establishing a Welsh government. Plaid Genedlaethol Cymru (English: National Party of Wales) was formed on 5 August 1925, by Moses Gruffydd, Fred Jones and Lewis Valentine, members of Byddin Ymreolwyr Cymru (Home Rule Army of Wales; literally, Self-Rulers' Army of Wales); and H. R. Jones, Saunders Lewis and David John Williams of Y Mudiad Cymreig (The Welsh Movement). Initially, home rule for Wales was not an explicit aim of the new movement; keeping Wales Welsh-speaking took primacy, with the aim of making Welsh the only official language of Wales.