2009–10 IFA Premiership

The 2009–10 IFA Premiership (known as the Carling Premiership for sponsorship reasons) was the 2nd season of the IFA Premiership, the highest level of league football in Northern Ireland, and the 109th season of Irish league football overall.

Linfield were champions, winning the league for the 49th time.

Summary
It began on 8 August 2009 and ended on 1 May 2010. Glentoran were the defending champions. On 27 April 2010, Linfield clinched the title after a 1–0 victory against Cliftonville at Windsor Park. On 14 May 2010, Institute were relegated to the 2010–11 IFA Championship, after losing the two-legged relegation play-off to Donegal Celtic, who took their place in the 2010–11 IFA Premiership.

Team changes from 2008–09
On 2 February 2009, Bangor's board announced that they would not be able to renew their domestic licence due to financial difficulties, and thereby would not compete in this season's premiership. They finished the 2008–09 season in 11th place. As a consequence, 12th-placed Dungannon Swifts, who were originally going to be directly relegated to the IFA Championship, earned the relegation play-off berth from Bangor. After a two-legged series against 2008–09 Championship runners-up Donegal Celtic, which ended in an aggregated 2–2 tie, Dungannon eventually retained their Premiership status on away goals.

Promoted from the Championship were 2008–09 champions Portadown, which marked their return to the highest football league of Northern Ireland after a one-year hiatus.

Matches 1–22
During matches 1–22 each team played every other team twice (home and away).

Matches 23–33
During matches 23–33 each team played every other team for the third time (either at home, or away).

Matches 34–38
During matches 34–38 each team played every other team in their half of the table once. As this was the fourth time that teams played each other this season, home sides in this round were chosen so that teams had played each other twice at home and twice away.

Promotion/relegation play-off
The promotion/relegation play-off was slightly altered this season because Donegal Celtic, runners-up of the 2009–10 IFA Championship, were the only IFA Championship club to hold the Domestic Club Licence required to participate in the Premiership. Lisburn Distillery, who finished in 11th place, avoided having to play a relegation play-off, which was passed down instead to Institute, who finished in 12th place and would normally have been automatically relegated. The first leg ended 0-0, with Institute having a penalty saved in injury-time at the end of the game. The second leg stayed goalless until the 85th minute, when Stephen McAlorum scored for Donegal Celtic, to relegate Institute to the 2010–11 IFA Championship.

Donegal Celtic won 1–0 on aggregate and were promoted, Institute were relegated