The Conclave is the governing body of the Citadel and the order of maesters. Composed of archmaesters, the Conclave elects a representative to the king, called the Grand Maester, who sits on the small council. All meetings of the Conclave are confidential in nature and conducted behind closed doors at the Citadel only.
A Storm of Swords
Varys informs Tyrion Lannister that Pycelle was restored to his position by Tywin Lannister after Tywin learned the Conclave of the Citadel was planning on naming Gormon Tyrell as Pycelle's replacement.