Both parliaments would be composed of a directly-elected House of Commons and an indirectly-elected Senate, with both lower chambers being elected by the Single Transferable Vote system of proportional representation.

[1][2] When the date of the elections was announced in the House of Commons, the Conservative MP Sir William Davison, who had been born in Broughshane, County Antrim, had asked "What is the object of holding elections in Southern Ireland when any candidates who do not support Sinn Fein would be shot?"

"[3] John Dillon and T. P. O'Connor both agreed that the Irish Party should not fight Sinn Féin for seats for the Southern parliament as things stood.

Of 52 seats, including Queen's University of Belfast, 40 were won by Unionists, 6 by the Nationalist Party and 6 by Sinn Féin.

Several well known republicans were elected: Éamon de Valera for South Down, Michael Collins for Armagh, Eoin MacNeill for Derry and Arthur Griffith for Fermanagh and Tyrone.

The Southern Ireland Commons was largely ignored, and only formally met twice: first in a brief 1921 session that only the four unionists attended, and then again in 1922 to approve the Anglo-Irish Treaty which established the Irish Free State.