In the OT, a collection of 150 self-contained poems and prayers without narrative contexts, traditionally ascribed to King David, but regarded by modern scholarship as mostly anonymous compositions of various dates and for undeclared occasions, which have to be inferred from the content.

The psalms have devices and techniques that are apparent in other Hebrew poetry, including parallelism, though there is no uniform system and the presence of a traceable metre is disputed. Some of the few psalms having a regular rhythm are Pss. 5, 29, 46, and 117. Ps. 29 (an early psalm, resembling literature found at Ugarit) contains parallelism in the first two verses. Other poetic devices include the use of repetitions and plays on words (e.g. Ps. 93: 4), refrains (Ps. 136), and acrostics (Ps. 111). Ps. 119 consists of 22 sections, each of eight lines, which begin with the same letter; the initial letters for each stanza are in turn the 22 letters of the Hebrew alphabet.

Psalms were composed for a variety of purposes over a long period of the nation’s history, certainly up to the Exile in Babylon (Ps. 137), and perhaps even to the Maccabean struggle (Ps. 44). But most modern scholars have been concerned less with possible historical settings than with the literary forms of psalms. Many are hymns celebrating deeds for which God is praised—the Creation (Ps. 8), the Exodus (Ps. 114), and the long course of events from Abraham to the invasion of Canaan—which presupposes a knowledge of Genesis and Exodus (Ps. 105), and so is probably a post-exilic composition. Another category is that of laments, sometimes in a personal form (Ps. 22), and sometimes in a communal cry of distress (Ps. 44). There are also personal thanksgivings, such as for recovery from illness (Ps. 30).

One group of psalms relates to the king of the line of David but it is uncertain whether those were composed during the time of the monarchy when a king on the throne was being honoured or, less probably, whether the psalms had in mind some future idealized king through whom divine blessings would be channelled to the nation. The king is regarded as a son of God, and there are references to his anointing and coronation (Pss. 2, 72, and 101). Some scholars believe that there was an annual enthronement festival. A royal wedding is the theme of Ps. 45, and Ps. 110 (which was to be an important text for the early Christian Church—e.g. Mark 12: 35–7) reflects the priestly role of the king in cultic ceremonies, acting on behalf of the whole people. The cultic context of these psalms is shown by Ps. 132, where the king and the Ark are associated in a thanksgiving for Jerusalem. Choral recitation in the Temple cult is suggested by psalms which contain antiphonal elements: Ps. 118 with liturgical instructions (verse 19) may have been for king and people to recite in turn; Ps. 15 was probably sung by pilgrims entering the building, perhaps at the feast of ingathering at the beginning of the year; they would be welcomed and invited to seek admission; they would respond by framing ten conditions (verses 2–5b); and then the priests pronounced a blessing (verse 5c). However, such is the diversity of forms that it is necessary to be cautious about the actual occasions for composition and use. Because there were changes in the cult over so many centuries scholars are reluctant to pronounce confidently about a context beyond that of liturgy in general for the Temple. Terms which appear, such as Selah (e.g. 3: 2), of uncertain meaning, and directions for the choir master at the head (e.g. Pss. 8–14) indicate the use of psalms with music in items of a service, such as a procession, or a blessing, or a petition.

The continuing liturgical use of the psalter argues for its having been specially put together for practical use in the Temple worship. Another view, however, proposes a literary emphasis: that it was compiled for teaching or theological purposes, expounding the everlasting kingship of God. On the latter view, the psalter is considered as a whole rather than as a collection of miscellaneous units, and the critical focus is more on the readers than on the original speakers of individual psalms in worship. But whether the psalter assumed its final shape through priests of the Temple as a book of hymns and prayers, or whether it was an anthology compiled by scribes, it is certain that the psalms have been an essential ingredient of both Jewish and Christian worship and the continuous liturgical usage has been a main factor in their being collected and preserved. Many psalms are among the Dead Sea discoveries at Qumran, and in the NT there are many quotations from the psalms. For example, sermons reported in Acts (e.g. 2: 25 ff.) quote Pss. 16 and 132 in support of belief in the resurrection of Christ, and Ps. 118 is regarded by the gospel of Matt. (21: 9) as foretelling Jesus to be the expected deliverer, leading a victory procession. By the 2nd cent. CE, the psalms were an established element in the Christian liturgy, and in due course became part of the daily office in religious houses whose members, both monks and nuns, were required to know the Latin psalms by heart before the invention of printing. It was a fixed text into which successive generations imported new meanings. Certain psalms cause difficulties for Christian readers, e.g. in the case of psalms (e.g. Ps. 88) which seems to deny any hope of life after death. In some psalms where there is uncertainty about the Hebrew text, or its meaning, long-standing familiarity with an incorrect translation has given a pastoral validity which does not exist when the translation is literally accurate. Thus, in Ps. 23 the phrase (verse 4) ‘though I walk through the valley of the shadow of death’ has been a comfort to mourners which ‘though I walk through the darkest valley’ does not.

The variety of English translations is witness to the difficulties and ambiguities of the Hebrew text. For modern readers there is also the embarrassment of using psalms which derive from a different culture. The ‘enemies’ who are denounced in pleas to God for justice may be ‘evil doers’ or foreign foes. Allegorical or typological interpretations have often been applied to diminish the offence of certain verses, e.g. Ps. 137: 8–9. The numbering of Psalms in AV and modern versions follows the Hebrew text; but older Catholic translations follow LXX and Vulgate, so that those numbers are one behind the Hebrew, until Ps. 147.

An additional psalm, Ps. 151, is found in early Greek versions, and was also in use at Qumran. It is held to be canonical by some Orthodox Christians in the East. It celebrates David’s killing of Goliath and thus taking away ‘reproach from the children of Israel’. In one English version (NRSV) Ps. 151 is included with the Apocrypha.