The Psalter
The Book of Psalms, or Psalms of David, is a book of the Old Testament containing 150 psalms, most of which were composed by King David, but some are the works of other prophets (e.g., Psalm 89, a prayer of Moses). The Psalms are songs of praise, prayers of forgiveness, prophecies about the coming Messiah, and express the entire range of human emotions and spiritual states. Since the beginning, it has been the primary hymnal and prayer book of the Christian Church, and the Psalms form the foundation of the daily services.
Vespers
Psalms 103, 140, 141, 129, 116.
Compline
Psalm 50, 69, 142 (during Lent also Psalms 4, 6, 12, 24, 30, 90, 101).
Midnight Office
Psalm 50, 118, 120, 133 (on Saturdays, Psalms 64, 65, 66, 67, 68, and 69 instead of 118)
Matins
Psalms 19, 20, 3, 37, 62, 87, 102, 142, 50, 148, 149, 150.
1st Hour
Psalms 5, 89, 100 (during certain fasts also Psalms 45, 91, 92).
3rd Hour
Psalms 16, 24, 50 (during certain fasts also Psalms 29, 31, 60).
6th Hour
Psalms 53, 54, 90 (during certain fasts also Psalms 55, 56, 69).
9th Hour
Psalms 83, 84, 85 (during certain fasts also Psalms 112, 137, 139).
The Divine Liturgy
102, 145, 33.
In addition to these fixed Psalms read at the services, we also read through entire book of Psalms once a week at Vespers and Matins. For liturgical use, the Psalter is divided into twenty kathísmata (literally ‘sittings’, since we are to sit during these readings), with each káthisma broken into three stanzas as below:
| Káthisma | 1st Stanza | 2nd Stanza | 3rd Stanza |
| 1 | Ps. 1–3 | Ps. 4–6 | Ps. 7–8 |
| 2 | Ps. 9–10 | Ps. 11–13 | Ps. 14–16 |
| 3 | Ps. 17 | Ps. 18–20 | Ps. 21–23 |
| 4 | Ps. 24–26 | Ps. 27–29 | Ps. 30–31 |
| 5 | Ps. 32–33 | Ps. 34–35 | Ps. 36 |
| 6 | Ps. 37–39 | Ps. 40–42 | Ps. 43–45 |
| 7 | Ps. 46–48 | Ps. 49–50 | Ps. 51–54 |
| 8 | Ps. 55–57 | Ps. 58–60 | Ps. 61–63 |
| 9 | Ps. 64–66 | Ps. 67 | Ps. 68–69 |
| 10 | Ps. 70–71 | Ps. 72–73 | Ps. 74–76 |
| 11 | Ps. 77 | Ps. 78–80 | Ps. 81–84 |
| 12 | Ps. 85–87 | Ps. 88 | Ps. 89–90 |
| 13 | Ps. 91–93 | Ps. 94–96 | Ps. 97–100 |
| 14 | Ps. 101–102 | Ps. 103 | Ps. 104 |
| 15 | Ps. 105 | Ps. 106 | Ps. 107–108 |
| 16 | Ps. 109–111 | Ps. 112–114 | Ps. 115–117 |
| 17 | Ps. 118:1–72 | Ps. 118:73–131 | Ps. 118:132–176 |
| 18 | Ps. 119–123 | Ps. 124–128 | Ps. 129–133 |
| 19 | Ps. 134–136 | Ps. 137–139 | Ps. 140–142 |
| 20 | Ps. 143–144 | Ps. 145–147 | Ps. 148–150 |
The kathísmata are usually read in the following manner:
| Day | Vespers | Matins |
| Sunday | No reading | Kathísmata 2–3 |
| Monday | Káthisma 6 | Kathísmata 4–5 |
| Tuesday | Káthisma 9 | Kathísmata 7–8 |
| Wednesday | Káthisma 12 | Kathísmata 10–11 |
| Thursday | Káthisma 15 | Kathísmata 13–14 |
| Friday | Káthisma 18 | Kathísmata 19–20 |
| Saturday | Káthisma 1 | Kathísmata 16–17 |
During Lent, the number of kathísmata is doubled, so that the Psalter is read in its entirety twice weekly.
Note that the Psalms in Orthodox Bibles (based on the Septuagint) used above differs from the numbering used in most English editions of the Scriptures (based on the Masoretic Texts):
| Septuagint | Masoretic | Septuagint | Masoretic |
| 1–8 | 1–8 | 115 | 116:10–19 |
| 9 | 9–10 | 116–145 | 117–146 |
| 10–112 | 11–113 | 146 | 147:1–11 |
| 113 | 114–115 | 147 | 147:12–20 |
| 114 | 116:1–9 | 148–150 | 148–150 |
In most editions of the Psalter, you will also find the Nine Biblical Odes, which are sung at Matins:
Ode 1, An Ode of Moses in the Exodus (Exodus 15:1–19)
Ode 2, An Ode of Moses in the Deuteronomy (Deuteronomy 32:1–43) — only sung on Tuesdays of Lent
Ode 3, A Prayer of Anna, the Mother of Samuel the Prophet (1 Kings 2:1–10)
Ode 4, A Prayer of Habakkuk the Prophet (Habakkuk 3:2–19)
Ode 5, A Prayer of Isaiah the Prophet (Isaiah 26:9–20)
Ode 6, A Prayer of Jonah the Prophet (Jonah 2:3–10)
Ode 7, A Prayer of the Holy Three Youths (Daniel 3:26–56)
Ode 8, The Hymn of the Holy Three Children (Daniel 3:57–88)
Ode 9, The Song of the Mother of God (Luke 1:46–55)