There were two governments in the 18th Dáil, which was elected at the 1965 general election held on 7 April 1965. Both were single-party Fianna Fáil governments, which had been in government since the 1957 election. The 11th government of Ireland (21 April 1965 – 10 November 1966) was led by Seán Lemass as Taoiseach and lasted for . The 12th government of Ireland (10 November 1966 – 2 July 1969) was led by Jack Lynch as Taoiseach and lasted for .
<!-- 11th government of Ireland redirects here--> 11th government of Ireland
Nomination of Taoiseach
The 18th Dáil first met on 21 April 1965. In the debate on the nomination of Taoiseach, Fianna Fáil leader and outgoing Taoiseach Seán Lemass, Fine Gael leader James Dillon, and Labour Party leader Brendan Corish were each proposed. The nomination of Lemass was carried with 72 votes in favour and 67 votes against. Lemass was re-appointed as Taoiseach by President Éamon de Valera.
{| class="wikitable"
|-
| colspan="3" bgcolor="#C0C0C0" align="center"|21 April 1965<br/>Nomination of Seán Lemass (FF) as Taoiseach<br/>Motion proposed by Seán MacEntee and seconded by Johnny Geoghegan<br/>Absolute majority: 73/144
|- bgcolor="#D8D8D8"
!width=80px|Vote
!width=425px|Parties
!width=80px|Votes
|-
| Yes || Fianna Fáil (72) ||
|-
| No || Fine Gael (47), Labour Party (20) ||
|-
| Absent or<br />Not voting || Ceann Comhairle (1), Independents (2), Labour Party (1), Clann na Poblachta (1) ||
|}
Members of the government
After his appointment as Taoiseach by the president, Seán Lemass proposed the members of the government and they were approved by the Dáil. They were appointed by the president on the same day.
{| class="wikitable"
|-
!Office
!colspan=2| Name
!Term
|-
|Taoiseach
|style="background-color: " |
|Seán Lemass
|1965–1966
|-
|Tánaiste
|rowspan=2 style="background-color: " |
|rowspan=2|Frank Aiken
|rowspan=2|1965–1966
|-
|Minister for External Affairs
|-
|Minister for Agriculture and Fisheries
|style="background-color: " |
|Charles Haughey
|1965–1966
|-
|Minister for Defence
|style="background-color: " |
|Michael Hilliard
|1965–1966
|-
|Minister for Education
|style="background-color: " |
|George Colley
|1965–1966
|-
|Minister for Finance
|style="background-color: " |
|Jack Lynch
|1965–1966
|-
|Minister for the Gaeltacht
|rowspan=2 style="background-color: " |
|rowspan=2|Mícheál Ó Móráin
|rowspan=2|1965–1966
|-
|Minister for Lands
|-
|Minister for Health
|style="background-color: " |
|Donogh O'Malley
|1965–1966
|-
|Minister for Industry and Commerce
|style="background-color: " |
|Patrick Hillery
|1965–1966
|-
|Minister for Justice
|style="background-color: " |
|Brian Lenihan
|1965–1966
|-
|Minister for Local Government
|style="background-color: " |
|Neil Blaney
|1965–1966
|-
|Minister for Posts and Telegraphs
|style="background-color: " |
|Joseph Brennan
|1965–1966
|-
|Minister for Social Welfare
|style="background-color: " |
|Kevin Boland
|1965–1966
|-
|Minister for Transport and Power
|style="background-color: " |
|Erskine H. Childers
|1965–1966
|-
|colspan="4"|
Changes 13 July 1966
Seán Flanagan was appointed to government on 6 July 1966.<br />A reshuffle took place after the establishment of the Department of Labour<br />under the Ministers and Secretaries (Amendment) Act 1966 on 13 July 1966.
|-
!Office
!colspan=2| Name
!Term
|-
|Minister for Education
|style="background-color: " |
|Donogh O'Malley
|1966
|-
|Minister for Health
|style="background-color: " |
|Seán Flanagan
|1966
|-
|Minister for Industry and Commerce
|style="background-color: " |
|George Colley
|1966
|-
|Minister for Labour
|style="background-color: " |
|Patrick Hillery
|1966
|}
;Change to department
Parliamentary Secretaries
On 21 April 1965, the government appointed the Parliamentary Secretaries on the nomination of the Taoiseach.
|-
|style="background-color: " |
|Seán Flanagan
|Parliamentary Secretary to the Minister for Industry and Commerce
|-
|style="background-color: " |
|Paudge Brennan
|Parliamentary Secretary to the Minister for Local Government
|}
Confidence in the government
On 8 July 1966, Labour leader Brendan Corish and Fine Gael leader Liam Cosgrave placed separate motions of no confidence in the government. They were debated as part of the debate on the summer adjournment. The motions were defeated, on votes of 50 to 66 and 54 to 66 respectively.
Resignation
Seán Lemass resigned as Fianna Fáil leader and Jack Lynch won the leadership election to succeed him on 9 November 1966. On the following day, Lemass resigned as Taoiseach.
<!-- 12th government of Ireland redirects here--> 12th government of Ireland
The 12th government was formed by Jack Lynch after the resignation of Seán Lemass.
Nomination of Taoiseach
On 10 November 1966, in the debate on the nomination of Taoiseach, Fianna Fáil leader Jack Lynch, Fine Gael leader Liam Cosgrave, and Labour Party leader Brendan Corish were each proposed. The nomination of Lynch was carried with 71 votes in favour and 64 votes against. Lynch was appointed as Taoiseach by President Éamon de Valera.
{| class="wikitable"
|-
| colspan="3" bgcolor="#C0C0C0" align="center"|10 November 1966<br/>Nomination of Jack Lynch (FF) as Taoiseach<br/>Motion proposed by Seán Lemass and seconded by Frank Aiken<br/>Absolute majority: 73/144
|- bgcolor="#D8D8D8"
!width=80px|Vote
!width=425px|Parties
!width=80px|Votes
|-
| Yes || Fianna Fáil (71) ||
|-
| No || Fine Gael (44), Labour Party (20) ||
|-
| Absent or<br />Not voting || Ceann Comhairle (1), Independents (2), Fine Gael (2), Labour Party (1), Clann na Poblachta (1) ||
|-
| Vacancies || 2||
|}
Members of the government
After his appointment as Taoiseach by the president, Jack Lynch proposed the members of the government and they were approved by the Dáil on 16 November 1966. They were appointed by the president on the same day.
{| class="wikitable"
|-
!Office
!colspan=2|Name
!Term
|-
|Taoiseach
|style="background-color: " |
|Jack Lynch
|1966–1969
|-
|Tánaiste
|rowspan=2 style="background-color: " |
|rowspan=2|Frank Aiken
|rowspan=2|1966–1969
|-
|Minister for External Affairs
|-
|Minister for Agriculture and Fisheries
|style="background-color: " |
|Neil Blaney
|1966–1969
|-
|Minister for Defence
|style="background-color: " |
|Michael Hilliard
|1966–1969
|-
|Minister for Education
|style="background-color: " |
|Donogh O'Malley
|1966–1968
|-
|Minister for Finance
|style="background-color: " |
|Charles Haughey
|1966–1969
|-
|Minister for the Gaeltacht
|rowspan=2 style="background-color: " |
|rowspan=2|Mícheál Ó Móráin
|1966–1969
|-
|Minister for Lands
|1966–1968
|-
|Minister for Health
|style="background-color: " |
|Seán Flanagan
|1966–1969
|-
|Minister for Industry and Commerce
|style="background-color: " |
|George Colley
|1966–1969
|-
|Minister for Justice
|style="background-color: " |
|Brian Lenihan
|1966–1968
|-
|Minister for Labour
|style="background-color: " |
|Patrick Hillery
|1966–1969
|-
|Minister for Local Government
|style="background-color: " |
|Kevin Boland
|1966–1969
|-
|Minister for Posts and Telegraphs
|rowspan=2 style="background-color: " |
|rowspan=2|Erskine H. Childers
|rowspan=2|1966–1969
|-
|Minister for Transport and Power
|-
|Minister for Social Welfare
|style="background-color: " |
|Joseph Brennan
|1966–1969
|-
|colspan=4|
Changes 26 March 1968
Following the death of Donogh O'Malley on 10 March 1968.
|-
!Office
!colspan=2| Name
!Term
|-
|Minister for Education
|style="background-color: " |
|Brian Lenihan
|1968–1969
|-
|Minister for Justice
|style="background-color: " |
|Mícheál Ó Móráin
|1968–1969
|-
|Minister for Lands
|rowspan=2 style="background-color: " |
|rowspan=2|Pádraig Faulkner
|rowspan=2|1968–1969
|-
|Minister for the Gaeltacht
|}
Parliamentary Secretaries
On 16 November 1966, the government appointed the Parliamentary Secretaries on the nomination of the Taoiseach.
|1966–1968
|-
|style="background-color: " |
|Paudge Brennan
|Parliamentary Secretary to the Minister for Local Government
|1966–1969
|-
|style="background-color: " |
|Patrick Lalor
|Parliamentary Secretary to the Minister for Posts and Telegraphs<br />Parliamentary Secretary to the Minister for Transport and Power
|1966–1969
|}
Constitutional referendums
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). They were put to referendums on 16 October 1968, and both were defeated by a margin of 39.2% to 60.8%. It was the second time a Fianna Fáil government had proposed to introduce FPTP, with a previous referendum defeated in 1959.
Confidence in the government
On 5 November 1968, Taoiseach Jack Lynch proposed a motion of confidence in the government, which was debated over three days. On 7 November, it was approved on a vote of 68 to 60.