Trinity School (formerly Carlisle Grammar School) is an 11–18 coeducational comprehensive secondary school and sixth form with academy status in Carlisle, Cumbria, England. It is a Church of England school with strong links to Carlisle Cathedral.

In 685 AD St Cuthbert, Bishop of Lindisfarne, visited Carlisle and founded both a school and a church. For the next 900 years the school continued around the grounds of the cathedral.

In 1545 Lancelot Salkeld, The Dean and Head of Chapter of Carlisle Cathedral took on responsibility for the school in the Cathedral close. The cathedral was rededicated to the Holy and Undivided Trinity. The school occupied buildings on West Walls, some of which are part of the diocesan offices to this day.

In 1883 it became Carlisle Grammar School and moved to Strand Road, into what is now the Carliol Building of the school, housing the Sixth Form Centre. Since that time, governors continue to be appointed by the Cathedral Foundation. The analogous girls' school was Carlisle County School for Girls, which became St Aidan's County High School.

As the movement towards comprehensive schools took shape, in 1968 the grammar school amalgamated with two local schools, the Margaret Sewell School (for girls) and the Creighton School (for boys), to become Trinity School, a Church of England comprehensive school, with all of the sites along Strand Road.

In the 1990s, Trinity School became grant-maintained, until 1999 when it became a Church of England Voluntary Aided School.

In 1998 the school was awarded Specialist School status and was designated as a Language College.

Recent developments include the Uganda Project, the USA Exchange Scheme, and overseas visits and links.