This is a timeline of the history of S4C (Welsh pronunciation: [ˌɛs ˌpɛdwar ˈɛk], Sianel Pedwar Cymru, meaning Channel Four Wales), originally the fourth-oldest terrestrial television channel in Wales.
Until 2010 it carried a mixture of Welsh language programmes and programmes from Channel 4 which was not broadcast on analogue TV in Wales.
In 2010, Channel 4 became available in Wales on all platforms and S4C became a Welsh-language-only channel.