- Eleven appointed by the Taoiseach (prime minister), see Senator nominated by the Taoiseach.
- Six elected by the graduates of certain Irish universities:
Three by graduates of the University of Dublin.
Three by graduates of the National University of Ireland.
- 43 elected from five special panels of nominees (known as Vocational Panels) by an electorate consisting of TDs (member of Dáil Éireann), senators and local councillors. Nomination is restrictive for the panel seats with only Oireachtas members and designated 'nominating bodies' entitled to nominate. Each of the five panels consists, in theory, of individuals possessing special knowledge of, or experience in, one of five specific fields. In practice the nominees are party members, often, though not always, failed or aspiring Dáil candidates:
- Administrative Panel: Public administration and social services (including the voluntary sector).
- Agricultural Panel: Agriculture and the fisheries.
- Cultural and Educational Panel: Education, the arts, the Irish language and Irish culture and literature.
- Industrial and Commercial Panel: Industry and commerce (including engineering and architecture).
- Labour Panel: Labour (organised or otherwise).
Under the Constitution of Ireland the general election for the Seanad must occur not later than 90 days after the dissolution of Dáil Éireann. The election occurs under the system of proportional representation by means of the single transferable vote (however in the panel constituencies each vote counts as 1000 meaning fractions of votes can be transferred). Membership is open to all Irish citizens over 21 and residing within Ireland, but a senator cannot also be a member of Dáil Éireann. However, as stated above, nomination to vocational panel seats is restricted; while nomination in the University constituencies requires signatures of 10 graduates.
In the case of a vacancy, by death, resignation or election to the European Parliament, a Seanad by-election take place. Seanad by-elections involve Oireachtas members only, giving the incumbent government an automatic majority.