A chapter house or chapterhouse is a building or room that is part of a cathedral, monastery or collegiate church in which meetings are held.
The chapter house comprises a large space, in order to hold all the monks of the monastery, and is often highly ornamented.
Many larger chapter houses are designed with vestibules for attendants and those waiting to be called, where opening onto a cloister does not provide such a space.
English chapter houses tend to be more elaborate and highly decorated than Continental ones, and the octagonal shape allowed for spectacular displays of stained glass, now mostly lost, though not at York.
Except at Westminster Abbey any paintings have been lost, but English designs, with their emphasis on carved arcades and windows, did not leave the large wall spaces found in most Continental chapter houses.
It was converted into the first home of what is now the Public Record Office (the national archives) soon after the English Reformation, and the late Gothic paintings added behind the seats (see gallery) were preserved hidden behind bookshelves until the 19th century.
In some Romanesque or Gothic monasteries, the entrance to the chapter house has an elaborate façade with a door surrounded by highly decorated archivolts, especially when it is a separate building.
The east side of the cloister on which the chapter house was often located was usually the first to be constructed; it would have been begun shortly after the church walls were built.