The 13th Seanad was in office from 1973 to 1977. An election to Seanad Éireann, the senate of the Oireachtas (Irish parliament), followed the 1973 general election to the 20th Dáil. The senators served until the close of poll for the 14th Seanad in 1977.

On 1 June 1973, James Dooge (FG) was proposed for the position of Cathaoirleach by Michael O'Higgins (FG) and seconded by Jack Fitzgerald (FG). He was elected without a division.

On 20 June 1973, Kit Ahern (FF) was proposed for the position of Leas-Chathaoirleach by Brian Lenihan (FF) and seconded by Seán Brosnan (FF). She was defeated by a vote of 18 to 31. Evelyn Owens (Lab) was proposed by Jack Fitzgerald (FG) and seconded by Michael Moynihan (Lab). She was elected by a vote of 30 to 18. Mary Robinson (Ind) supported the election of Ahern, but abstained in the vote on Owens.

There are a total of 60 seats in the Seanad: 43 were elected on five vocational panels, 6 were elected from two university constituencies and 11 were nominated by the Taoiseach.

The following table shows the composition by party when the 13th Seanad first met on 1 June 1973.