For reading at the Orthodox services, the Psalter is divided into 20 sections called kathismas (“sittings”); each kathisma is further subdivided into three antiphons (also called stases – singular stasis). At Great Vespers of the Lord’s day, (Saturday evening), the entire first kathisma is read (often sung and abbreviated in parish practice). At feasts on other days of the week, only the first stasis, or antiphon, of the first kathisma (“Blessed is the man”) is read. On certain great feasts of the Lord there is no Psalter reading. There is also no Psalter reading on Sunday evening, with the same exception. At Daily Vespers, the appointed kathisma is read, as determined from the table below. As the table shows, the Psalter reading at daily vespers for a good portion of the year is the 18th kathisma, which is the kathisma consisting of the short Psalms of Ascent. The table shows the kathismas appointed to be read at vespers throughout the year. There are no psalter readings at vespers in Bright Week. At other times of the year, if there is a psalter reading at Great Vespers, it is always “Blessed is the man” (that is, Psalms 1-3). 
Kathisma Readings
Psalter Readings/Kathisma Readings at Vespers
