The High School of Glasgow is a private, co-educational day school in Glasgow, Scotland. The original High School of Glasgow was founded as the choir school of Glasgow Cathedral in around 1124, and is the oldest school in Scotland, and the twelfth oldest in the United Kingdom. On its closure as a selective grammar school by Glasgow City Corporation in 1976, it immediately continued as a co-educational independent school as a result of fundraising activity by its Former Pupil Club and via a merge by the Club with Drewsteignton School. The school maintains a relationship with the Cathedral, where it holds an annual service of commemoration and thanksgiving in September. It counts two British Prime Ministers, two Lords President and the founder of the University of Aberdeen among its alumni.

Private schools in the United Kingdom are schools that require fees for admission and enrollment. Some have financial endowments, most are governed by a board of governors, and are owned by a mixture of corporations, trusts and private individuals. They are independent of many of the regulations and conditions that apply to state-funded schools. For example, the schools do not have to follow the National Curriculum, although many such schools do.