In sociology and anthropology, an age grade or age class is a form of social organization based on age, within a series of such categories, through which individuals pass over the course of their lives.

This is in contrast to an age set, to which individuals remain permanently attached as the set itself becomes progressively more senior.

The number of age classes, the determining ages and the terminology vary significantly between traditions. Even within a single society, a person may belong to several overlapping grades in different spheres of life, e.g. per year a different school class and yet for several years on end a child, then an adolescent, finally an adult.

In tribal societies entry into an age grade - generally gender-separated - is often marked by an initiation rite, which may be the crowning of a long and complex preparation, sometimes in retreat. After a period of some years, during which they often perform certain common activities, alone or under senior guidance, members may be initiated either collectively or individually into a more senior age grade. This progression is often accompanied by the revelation of secret knowledge. In most cultures, age grade systems, as with age sets, are the preserve of men, and it is the older men who control a society's secret knowledge, collectively or restricted to a council of elders and/or specific positions such as shaman entrusted with the preparation of initiants.

Coordinates: 54°19′19″N 2°31′54″E / 54.32182°N 2.53153°E / 54.32182; 2.53153

Sedbergh School is an independent day and boarding school in Sedbergh, Cumbria. It comprises a junior school for children aged 4 to 13 and the main school.

Roger Lupton is thought to have been born at Cautley in the parish of Sedbergh in 1456 and he provided for a Chantry School in Sedbergh in 1525 while he was Provost of Eton. By 1528, land had been bought, a school built, probably on the site of the present School Library, and the foundation deed had been signed, binding the School to St John's College, Cambridge and giving the College power over the appointment of Headmasters. This link to St John's College probably saved Sedbergh in 1546-48 when most chantries were dissolved and their assets seized by Henry VIII's Commission.

Sedbergh was re-established and re-endowed as a Grammar School in 1551 and the fortunes of the School in the coming centuries seem to have depended very much on the character and abilities of the Headmasters with pupil numbers fluctuating and reaching as low a total as 8 day boys in the early 19th century.