There were two governments of the 21st Dáil, which was elected at the 1977 general election on 16 June 1977. Both were single-party majority Fianna Fáil governments. The 15th government of Ireland was led by Jack Lynch as Taoiseach and lasted for 890 days. The 16th government of Ireland was led by Charles Haughey and lasted for 568 days.

The 1977 Irish general election to the 21st Dáil was held on Thursday, 16 June, following the dissolution of the 20th Dáil on 25 May by President Patrick Hillery on the request of Taoiseach Liam Cosgrave. The general election took place in 42 Dáil constituencies throughout Ireland for 148 seats in Dáil Éireann, the house of representatives of the Oireachtas, an increase of four seats with a significant revision of constituencies under the Electoral (Amendment) Act 1974. The election is regarded as a pivotal point in twentieth-century Irish politics. Jack Lynch led Fianna Fáil to a landslide election win, clearly defeating the outgoing Fine Gael–Labour government.