Song of Degrees, Song of Steps, Gradual Psalms, Song of Ascents (Hebrew: שיר המעלות, Shir Hama'aloth) or Hymn of Degrees is a title given to fifteen of the Psalms, that each starts with the words Shir Hama'alot (A Song of Ascents) and which are numbered 120–134 in the Masoretic recension (119–133 in the Septuagint). The probable origin of this name is the circumstance that these psalms came to be sung by the people on the ascents or goings up to Jerusalem to attend the three pilgrim festivals (). They were well suited for being sung, by their poetic form and the sentiments they express. "They are characterized by brevity, by a key-word, by epanaphora [i.e., repetition], and by their epigrammatic style.... More than half of them are cheerful, and all of them hopeful."
They are sometimes called "Pilgrim Songs." Four of them (122, 124, 131 and 133) are claimed in their ascriptions to have been by David, and one (127) by Solomon, the rest being anonymous. Some modern scholars do not believe that these ascriptions can be taken literally, although they give evidence that helps in dating of the Psalms and identifying their original use.
Many early hermits observed the practice of reciting the entire Psalter daily, coenobitic communities would chant the entire Psalter through in a week, so these psalms would be said on a regular basis, during the course of the Canonical hours.
During Great Lent the Eighteenth Kathisma is read every weekday (Monday through Friday evening) at Vespers, and on Monday through Wednesday of Holy Week. In the Slavic usage this Kathisma is also read from the apodosis of the Exaltation of the Cross up to the forefeast of the Nativity of Christ, and from the apodosis of Theophany up to the Sunday of the Prodigal Son. The reason for this is that the nights are longer in winter, especially in the northern latitudes, so during this season three Kathismas will be chanted at Matins instead of two, so in order to still have a reading from the Psalter at Vespers, the Eighteenth Kathisma is repeated.
Symbolically, the anabathmoi are chanted as a reminder that Christians are ascending to the Heavenly Jerusalem, and that the spiritual intensity of the service is rising as we approach the reading of the Gospel.