Thekliros (Greek: κλῆροςklēros, plural κλῆροιklēroi;Slavonic: клиросъ, "kliros" or sometimes крилосъ, "krilos") is the section of anEastern Orthodox,Armenian, orEastern Catholic church dedicated to thechoir. It refers both to the general space in whichchanters or singers assemble for the services, as well as to the actual music stand or shelves on which music is stored and read.

The name derives from the Greek word for "lot", since originally those who read and sang were chosen by lot.^[1]

Historically, incathedrals,monasteries and larger establishments such as chapels belonging toseminaries and major parishes, there would have been kliroi on both right and left sides of the church. The result is two choirs which singantiphonally, much as monastic and cathedral choirs of the Western Churches still have today. This was the practice in theByzantine Imperial Cathedral ofHagia Sophia, inConstantinople, whose historical liturgical practice became the standard for all churches following theByzantine liturgical tradition.

This arrangement presupposes a number of singers on each side, adding up to a reasonably large total, and two highly trained chanters skilled in leading the services. Unfortunately, highly trained chanters are exceedingly rare today, and most churches have only the one kliros, often to the right of theiconostasis. Nevertheless, some patriarchal cathedrals, larger monastic communities, seminaries, and places with sufficient resources and singers, may continue to have two kliroi.

TheRussian Orthodox Church will often have, in addition to a kliros by the iconostasis, achoir loft above the great doors of the west entrance of the church.

In churches of theGreek and some parts of theRussian tradition, chanters and men who sing at the kliros will often wear a blackriassa (outer-cassock).

In theArmenian tradition, all members of the choir at the kliros wear astikharion (robe made out of fine material).

• Kliros - Russian Orthodox free archive of church singing materials
• Клирос в интерьере русского храма в XVII—XVIII веках