In the Greek Orthodox Church, there is an important and long-standing tradition of praying for our departed sisters and brothers. Saturday (except for Lazarus Saturday and Holy Saturday) is the day of the week that is traditionally reserved for those who have fallen asleep because our Lord’s own salvific passing took place on Great and Holy Saturday.
While each Saturday provides an opportunity for the remembrance of those who have fallen asleep, there are two main Saturdays every year known as ’Saturday of Souls,’ which are designated specifically for this purpose: the Saturday before Meatfare Sunday, which is this Saturday, February 18, 2023, and the Saturday before Pentecost.
It is important to highlight that many traditions in the Church started locally, and some have been adopted on a larger scale or even more formally by the Church. This is demonstrated by the fact that in some regions or local Churches, the Saturday before the feast of Saint Demetrios (October 26th) is celebrated as a Saturday of Souls, and more local Churches have been adopting this tradition.
Most Churches also observe two additional Saturdays of Souls: one on the Saturday before Cheesefare Sunday (where we commemorate all the holy men and women who excelled in asceticism) and on the Saturday of the first week of Great Lent (where we celebrate the miracle of kollyva by the Great Martyr and Saint Theodore the Tyro).
Source: Metropolis of Zambia