S
- Sacred Heart College, Omagh, County Tyrone
- Saintfield High School, Saintfield, County Down
- Scoil Iósaef (Sruth), Irish-medium school, County Tyrone
- Shimna Integrated College, Newcastle, County Down
- Slemish Integrated College, Ballymena, County Antrim
- Sperrin Integrated College, Magherafelt, County Londonderry
- St. Aidan's High School, Enniskillen, County Fermanagh
- St. Benedict's College, Randalstown, County Antrim
- St. Brigid's College, Derry
- St. Brigid's High School, Armagh
- St. Catherine's College, Armagh
- St. Cecilia's College, Derry
- St. Ciaran's High School, Dungannon, County Tyrone
- St. Colm's High School, Belfast
- St. Colman's High School, Ballynahinch, County Down
- St. Colmcille's High School, Crossgar, County Down
- St. Colm's High School, Draperstown, County Londonderry
- St. Columb's College, Derry
- St. Columba's College, Newtownards, County Down
- St. Columban's College, Kilkeel, County Down
- St. Columbanus' College, Bangor, County Down
- St. Comhghall's Secondary School, Enniskillen, County Fermanagh
- St. Eugene's College, Rosslea, County Fermanagh
- St. Eugene's High School, Castlederg, County Tyrone
- St. Fanchea's College, Enniskillen, County Fermanagh
- St. Gabriel's School, Belfast
- St. Gemma's High School, Belfast
- St. Genevieve's High School, Belfast
- St. John's College, Portadown, County Armagh
- St. John's Business and Enterprise College, Dromore, County Tyrone
- St Joseph's Boys' High School, Newry, County Down
- St. Joseph's Boys' School, Derry
- St. Joseph's College, Belfast
- St. Joseph's College, Coleraine, County Londonderry
- St. Joseph's College, Enniskillen, County Fermanagh
- St. Joseph's High School, Coalisland, County Tyrone
- St. Joseph's High School, Crossmaglen, County Down
- St. Joseph's High School, Plumbridge, County Tyrone
- St. Killian's College, Carnlough, County Antrim
- St. Louise's Comprehensive College, Belfast
- St. Malachy's High School, Castlewellan, County Down
- St. Mark's High School, Warrenpoint, County Down
- St. Mary's College, Ballymena, County Antrim
- St. Mary's College, Enniskillen, County Fermanagh
- St. Mary's College, Derry
- St. Mary's High School, Downpatrick, County Down
- St. Mary's High School, Enniskillen, County Fermanagh
- St. Mary's High School, Lurgan, County Armagh
- St. Mary's High School, Newry, County Down
- St. Mary's High School, Limavady, County Londonderry
- St. Patrick's College, Maghera, County Londonderry
- St Patrick's College, Ballymena, County Antrim
- St Patrick's College, Belfast
- St Patrick's Grammar, Dungannon, County Tyrone
- St Patrick's College Dungannon Co Tyrone Northern Ireland
- St Patrick's College, Derry
- St. Patrick's College, Banbridge, County Down
- St. Patrick's High School, Keady, County Armagh
- St. Patrick's High School, Lisburn, County Antrim
- St. Patrick's and St. Brigid's College, Claudy, County Londonderry
- St. Paul's College, Coleraine, County Londonderry
- St. Paul's High School, Bessbrook, County Armagh
- St. Paul's Junior High School, Lurgan, County Armagh
- St. Peter's High School, Derry
- St. Pius X College, Magherafelt, County Londonderry
- St. Rose's High School, Belfast
- Strabane High School, Strabane, County Tyrone
- Strangford Integrated College, Carrowdore, County Down
- Strabane Grammar school, Strabane, County Tyrone
Read more about this topic: List Of Secondary Schools In Northern Ireland