The Te Deum (also known as Ambrosian Hymn or A Song of the Church) is an early Christian hymn of praise. The title is taken from its opening Latin words, Te Deum laudamus, rendered as "Thee, O God, we praise".
The hymn remains in regular use in the Catholic Church in the Office of Readings found in the Liturgy of the Hours, and in thanksgiving to God for a special blessing such as the election of a pope, the consecration of a bishop, the canonization of a saint, a religious profession, the publication of a treaty of peace, a royal coronation, etc. It is sung either after Mass or the Divine Office or as a separate religious ceremony. The hymn also remains in use in the Anglican Communion and some Lutheran Churches in similar settings.
In the traditional Office, the Te Deum is sung at the end of Matins on all days when the Gloria is said at Mass; those days are all Sundays outside Advent, Septuagesima, Lent, and Passiontide; on all feasts (except the Triduum) and on all ferias during Eastertide. Before the 1962 reforms, neither the Gloria nor the Te Deum were said on the feast of the Holy Innocents, unless it fell on Sunday, as they were martyred before the death of Christ and therefore could not immediately attain the beatific vision. A plenary indulgence is granted, under the usual conditions, to those who recite it in public on New Year's Eve.
In the Liturgy of the Hours of Pope Paul VI, the Te Deum is sung at the end of the Office of Readings on all Sundays except those of Lent, on all solemnities, including the octaves of Easter and Christmas, and on all feasts. It is also used together with the standard canticles in Morning Prayer as prescribed in the Anglican Book of Common Prayer, in Matins for Lutherans, and is retained by many other churches of the Reformed tradition. Part of the setting of the Te Deum by Marc-Antoine Charpentier is the anthem of Eurovision. The instrumental prelude is played at the opening, intervals and closing of the show.
Authorship is traditionally ascribed to Saints Ambrose and Augustine, on the occasion of the latter's baptism by the former in AD 387. It has also been ascribed to Saint Hilary, but Catholic-Forum.com says "it is now accredited to Nicetas, bishop of Remesiana; (4th century)".
The petitions at the end of the hymn (beginning Salvum fac populum tuum) are a selection of verses from the book of Psalms, appended subsequently to the original hymn.
The hymn follows the outline of the Apostles' Creed, mixing a poetic vision of the heavenly liturgy with its declaration of faith. Calling on the name of God immediately, the hymn proceeds to name all those who praise and venerate God, from the hierarchy of heavenly creatures to those Christian faithful already in heaven to the Church spread throughout the world. The hymn then returns to its credal formula, naming Christ and recalling his birth, suffering and death, his resurrection and glorification. At this point the hymn turns to the subjects declaiming the praise, both the universal Church and the singer in particular, asking for mercy on past sins, protection from future sin, and the hoped-for reunification with the elect.
The text has been set to music by many composers, with settings by Haydn, Mozart, Berlioz, Verdi, Bruckner, Furtwängler, Dvořák, Britten, Kodály, and Pärt among the better known. Jean-Baptiste Lully wrote a setting of Te Deum for the court of Louis XIV of France, and received a fatal injury while conducting it. The prelude to Marc-Antoine Charpentier's setting (H.146) is well known in Europe on account of its being used as the theme music for some broadcasts of the European Broadcasting Union, most notably the Eurovision Song Contest. Sir William Walton's Coronation Te Deum was written for the coronation of Queen Elizabeth II in 1953. Other English settings include those by Thomas Tallis, William Byrd, Henry Purcell, and Edward Elgar, as well as three settings each by George Frideric Handel and Charles Villiers Stanford.
A version by Father Michael Keating is popular in some Charismatic circles. Mark Hayes wrote a setting of the text in 2005, with Latin phrases interpolated amid primarily English lyrics. In 1978, British hymnodist Christopher Idle wrote God We Praise You, a version of the text in 184.108.40.206.D meter, set to the tune Rustington. British composer John Rutter has composed two settings of this hymn, one entitled Te Deum and the other Winchester Te Deum. Igor Stravinsky set the first 12 lines of the text as part of The Flood in 1962. Antony Pitts was commissioned by the London Festival of Contemporary Church Music to write a setting for the 2011 10th Anniversary Festival. The 18th-century German hymn Großer Gott, wir loben dich is a free translation of the Te Deum, which was translated into English in the 19th century as "Holy God, we praise thy name."
Latin and English text 
|Latin text||Translation from the Book of Common Prayer|
Te Deum laudamus:
We praise thee, O God :
In the Book of Common Prayer, verse is written in half-lines, at which reading pauses, indicated by colons in the text.
- Te Deum by Hector Berlioz
- Te Deum Laudamus, the fourth section of Symphony No. 1 in D minor ("Gothic") (1919-1927) by Havergal Brian
- Te Deum by Benjamin Britten
- Te Deum by Anton Bruckner
- Te Deum by Marc-Antoine Charpentier
- Te Deum by Antonín Dvořák
- Utrecht Te Deum and Jubilate (1713), Dettingen Te Deum (1743) by George Frideric Handel
- Te Deum by Joseph Haydn
- Te Deum by Herbert Howells
- Te Deum by Zoltán Kodály
- Te Deum by Jean-Baptiste Lully
- Te Deum by James MacMillan
- Te Deum by Piers Maxim
- Te Deum by Felix Mendelssohn
- Te Deum by Wolfgang Amadeus Mozart
- Te Deum by Arvo Pärt
- Te Deum by Krzysztof Penderecki
- Te Deum by Ilia II of Georgia
- Festival Te Deum and Te Deum Laudamus by Arthur Sullivan
- Te Deum, the final part of Quattro Pezzi Sacri by Giuseppe Verdi
- "The Te Deum (cont.)". Musical Musings: Prayers and Liturgical Texts — The Te Deum. CanticaNOVA Publications. Retrieved 2007-07-07.
- "Holy Innocents". Catholic Encyclopedia. New York: Robert Appleton Company. 1913. Retrieved 2010-04-14.
- "Te Deum". Retrieved 2011-12-31.
- "General Instruction of the Liturgy of the Hours". Retrieved 2007-12-02.
- http://www.catholic-forum.com/saints/pray0134.htm, consulted 14-10-2010
- Christopher Idle, Jubilate Group
- The Worshiping Church page 42 | Hymnary.org
- Welcome to LFCCM
- February 2011 from Jerusalem to Jericho
- Texts on Wikisource:
- Catholic Encyclopedia entry
- Te Deum (Music Ensemble that regularly performs Te Deum settings)
-  Piers Maxim