'''Concelebration''' is the act of multiple [[clergy]] conducting divine
[[services ]] together. [[Rubrics]] dictate what changes are made in the services when a concelebration occurs, as distinct from when the services are performed by only one [[priest]] or also a [[deacon]]. Concelebration is often a sign of full fellowship and [[full communion|communion]] between [[jurisdiction]]s which recognize each other as fully Orthodox.
[[Hierarchical services]] are a special type of concelebration including one or more [[bishop]]s, significantly altering the text and movement in a service.