The 11th government of Ireland (21 April 1965 – 10 November 1966) was led by Seán Lemass as Taoiseach and lasted for 1 year, 203 days.

The 12th government of Ireland (10 November 1966 – 2 July 1969) was led by Jack Lynch as Taoiseach and lasted for 2 years, 234 days.

[7][8]A reshuffle took place after the establishment of the Department of Labourunder the Ministers and Secretaries (Amendment) Act 1966 on 13 July 1966.

Seán Lemass resigned as Fianna Fáil leader and Jack Lynch won the leadership election to succeed him on 9 November 1966.

[16] After his appointment as Taoiseach by the president, Seán Lemass proposed the members of the government and they were approved by the Dáil on 16 November 1966.

[21] The government proposed the Third Amendment of the Constitution Bill 1968, which would have allowed for divergence in the ratio of population to representation across Dáil constituencies, and the Fourth Amendment of the Constitution Bill 1968, which would have altered the electoral system from proportional representation by means of the single transferable vote (PR-STV) to first past the post (FPTP).