Membership of the cabinet is regulated by Article 28 of the
Constitution of Ireland and by the
Ministers and Secretaries Acts 1924 to 2017.
 The Irish constitution requires the government to consist of between seven and fifteen members,
 all of whom must be a member of the
Since the formation of the
12th Government of Ireland in 1966,
 all Irish cabinets have been formed with the constitutional maximum of fifteen ministers. The total sometimes falls below this number for brief periods following the resignation of individual ministers or the withdrawal of a party from a coalition.
No more than two members of the Government may be members of
Seanad Éireann, the
upper house of the legislature.
 As a result, all other members of the government must be members of
Dáil Éireann, the lower house. The Taoiseach, Tánaiste and
Minister for Finance must be members of the Dáil.
In practice, however, the members of the government are invariably members of the Dáil. Since the adoption of the 1937 constitution, two ministers have been appointed from the Seanad: only
Seán Moylan who served in 1957 as
Minister for Agriculture and
James Dooge who served as
Minister for Foreign Affairs from 1981 to 1982.
Joseph Connolly, a member of the
Free State Seanad, had served in the
Executive Council of the Irish Free State
 from 1932 to 1933 as
Minister for Posts and Telegraphs,
 and from 1933 to 1936 as
Minister for Lands and Fisheries.
Members of the government in charge of
Department of State are designated "
Ministers of Government" (before 1977 a "Minister of State").
 For distinction, "
Ministers of State" (known before 1977 as "
Parliamentary Secretaries") — informally called "junior ministers" — are not members of Government. A Government Minister (before 1977 a "Minister of State") is usually in charge of a
Department of State and thus technically a "Minister of Government". A
minister without portfolio may be appointed to the Government who is not the head of a Department of State; this occurred in 1939 during the period of
the Emergency when
Frank Aiken served as
Minister for the Co-ordination of Defensive Measures until 1945.