The present article addresses the history of the preparations of the Pan-Orthodox Council since 1923, when the Pan-Orthodox Conference was held in Istanbul, until January 2016, when the Synaxis of the Primates was held in Chambésy, Switzerland. This article describes distinctive features and main events of the pre-conciliar process at its different stages as well as retraces the formation of the Council’s agenda and the evolution of its preparatory procedure.