The General Secretariat for the Synod has published this Vademecum (or handbook) to indicate the guiding principles that will direct the path of the Synod on Synodality. The solemn opening of the Synod will take place in Rome on October 9-10, 2021, and in the particular Churches on October 17; and will conclude in the Vatican in 2023 with the assembly of bishops from around the world.