Evensong is a church service traditionally held near sunset focused on singing psalms and other biblical canticles. It is loosely based on the canonical hours of vespers and compline. Old English speakers translated the Latin word vesperas as æfensang, which became 'evensong' in modern English. Typically used in reference to the Anglican daily office's evening liturgy, it can also refer to the pre-Reformation form of vespers or services of evening prayer from other denominations, particularly within the Anglican Use of the Catholic Church.

From Late Antiquity onwards, the office of vespers normally included psalms, the Magnificat, a hymn, and other prayers. By the Early Middle Ages, it became common for secular clergy to combine vespers and compline. By the sixteenth century, worshippers in western Europe conceived 'evensong' as vespers and compline performed without break. Modern Eastern Orthodox services advertised as 'vespers' often similarly conclude with compline, especially as part of the all-night vigil.

When the English reformation produced the Book of Common Prayer, it provided a version of evensong that abbreviated the secular version of vespers and compline, drawing on the Use of Sarum. Nearly all its elements are taken from medieval service books, with only minor changes to the order in which they appear.

Evensong was initially sung entirely to plainsong. Musicians gradually created polyphonic settings of its music, especially of the Magnificat.

The first musical setting of the Book of Common Prayer, by John Marbeck, provided a simplified version of traditional chant settings. It remains unclear whether plainsong remained a common feature of evensong in the Church of England after the sixteenth century. Metrical psalms and Anglican Chant were also developed as alternate methods of singing the psalms and canticles.

In choral evensong, all of the service is sung or chanted by the officiating minister and a choir. In cathedrals, or on particularly important days in the church calendar, the canticles are performed in elaborate settings. In churches where a choir is not present, simpler versions of the psalms and canticles are usually sung by the congregation, sometimes with responses and collects spoken rather than sung. Said evening prayer services with the musical setting omitted are also sometimes referred to as evensong.

A number of composers have contributed settings of the canticles. These range from late Renaissance composers such as Thomas Tallis, William Byrd and Orlando Gibbons, through Victorian composers such as Charles Villiers Stanford, Thomas Attwood Walmisley to later masters of the form such as Herbert Murrill, Basil Harwood, Herbert Howells, Michael Tippett, Giles Swayne, and Arvo Pärt (who composed a Magnificat and Nunc dimittis at different times).

In High Church parishes, the service may conclude with Benediction of the Blessed Sacrament (or a modified form of "Devotions to the Blessed Sacrament") and the carrying of the reserved sacrament under a humeral veil from the high altar to an altar of repose, to the accompaniment of music.