Limavady's three secondary schools sit within walking distance of each other along Ballyquin Road and Irish Green Street - Limavady Grammar, Limavady High School, and St Mary's High School. The clustering means pupils from different backgrounds and abilities pass each other every morning on the pavements. Limavady Grammar is non-denominational and features a broad mix of pupils from across County Londonderry. Admissions are based on academic selection - until November 2023 via the AQE common entrance assessment, since then via the new SEAG (Schools' Entrance Assessment Group) test. The grammar is co-educational, has been since its founding, and that was unusual when it opened. Northern Ireland's selective schools were overwhelmingly single-sex until recent decades.

The origins of Limavady Grammar can be traced back to a late-nineteenth-century foundation, but the current school was established in 1957. It originally occupied the site that now houses Limavady High School. The move to the present site on Ballyquin Road came later, with major extensions in 1982 (new science labs and a sports hall) and 1998 (twenty-two new classrooms including three IT rooms). The mission statement is "Learning, Caring, Preparing for Life" - the kind of phrase that could grace any school motto in the British Isles but which the school has tried to take seriously through its emphasis on extracurricular breadth as well as academic achievement.

Rugby is the main boys' sport. The school fields two teams at each age level from U12 to Medallion, with a 1st XV and 2nd XV at senior level. The 1st XV plays in the Danske Bank Schools Cup - one of the great Ulster school rugby competitions. Past pupil Derek McAleese earned a single Ireland cap against France in 1992 and played many times for Ulster. Hockey is the main girls' sport. Football, cricket, netball, tennis, athletics, even a surf club fill out the calendar. In September 2007 the school opened a synthetic astroturf pitch, jointly funded by the Big Lottery Fund (£585,000) and Limavady Borough Council (£50,000) - a community facility used by clubs in the area, day and evening. The opening was attended by Edwin Poots MLA, then Minister for Sport.

The school's French Debating Society won the Northern Ireland NICILT Post-16 French Debating Championship in 2006, 2007, 2009, and 2010 - four titles in five years. The choir, the orchestra, the jazz band, the brass band, and the traditional Irish music group perform at festivals including the Limavady Jazz & Blues Festival held in the town each summer. There is a Chemistry Club, a Technology Club, a Computer Club, an Art Club, drama, public speaking, photography, and pottery. The Duke of Edinburgh Award scheme is taken up by the majority of pupils each year, with a residential introductory event held at White Park Bay on the Antrim coast. The breadth is the point - the grammar tries to be everything an academically-selective school is supposed to be, in a town that does not have the cultural overhang of Belfast or Dublin.

Jason Smyth holds the most stellar record - six Paralympic golds, world records, and a sprint career that ended on his own terms. He is one of the most decorated Paralympians ever to come out of Ireland. Chloe MacCombe, a Northern Irish paratriathlete, won a silver medal at the Commonwealth Games. These two names dominate the school's recent alumni board. Other past pupils have gone into law, medicine, politics, and broadcasting - the standard destinations of a selective grammar - without quite the same individual prominence. The grammar's success is mostly measured in collective rather than individual terms: consistent rankings in the upper tier of UK schools, university destinations across Britain and Ireland, and a steady stream of pupils who carry their Ballyquin Road education into careers all over the world.