O Antiphons are traditionally recited during Advent Liturgy of the Hours. They are so named because each begins with "O"; they are also called the "Great Antiphons." The O Antiphons are also sometimes used to make private novenas from December 17th to December 23rd.
The Advent hymn, O Come, O Come, Emmanuel is probably the most famous rendition of the O Antiphons.
To pray the O Antiphons with your family or by yourself, Download O_Antiphons.pdf (136.6K)
For more on O Antiphons, check out these websites:
Catholic Education Resource Center: http://www.catholiceducation.org/articles/religion/re0374.html
Catholic Encyclopedia: http://www.newadvent.org/cathen/11173b.htm
