The 108 members chosen by voters in last week's Northern Ireland Assembly elections have gathered at Stormont.
DUP leader Peter Robinson has been reappointed to the position of First Minister after being nominated party colleague Sammy Wilson, while Sinn Féin's Martin McGuinness has been returned as Deputy First Minister after being nominated by Pat Doherty.
The DUP's Willie Hay has been re-elected Speaker of the Assembly.
The Foyle MLA was nominated by Mr McGuinness and seconded by Mr Robinson.
Sinn Féin's Francie Molloy, the SDLP's John Dallat and the UUP's Roy Beggs have been appointed deputy speakers.
The allocation of ministerial portfolios may have to wait until Monday.
The positions are given out based on the number of Assembly seats won in last week's elections.
The DUP is entitled to four ministerial posts, Sinn Féin three, and the Ulster Unionists, the SDLP and the Alliance party one each.
The UUP suffered a setback yesterday after Independent David McClarty decided against rejoining its ranks.
If Mr McClarty had rejoined, he would have given the party enough numbers to gain a second ministerial position.