L
- Lagan College, Belfast, County Antrim
- Larne Grammar School, Larne, County Antrim
- Limavady Grammar School, Limavady, County Londonderry
- Loreto College, Coleraine, County Londonderry
- Loreto Grammar School, Omagh, County Tyrone
- Lumen Christi College, Derry
- Lurgan College, Lurgan, County Armagh
Read more about this topic: List Of Grammar Schools In Northern Ireland