A Commemoration ball is a formal ball held by one of the colleges of the University of Oxford in the 9th week of Trinity Term, the week after the end of the last Full Term of the academic year, which is known as "Commemoration Week". Commemoration balls are held by different colleges each year, following a cycle by which each college holds a ball every three years.
Commemoration Week is so known because of the ceremonies in commemoration of the benefactors of the university that are held then, namely the Commemoration Day sermon formerly held (until 2006) on the Sunday, and the Encaenia ceremony (where the annual Creweian Oration in honour of benefactors is given) and garden party on the Wednesday of that week. Commemoration Week was formerly one of two occasions when balls were traditionally held, the other being Eights Week, the 5th week of Trinity term when the Summer Eights rowing races occur. Eights balls are nowadays comparatively rare.
There is no formal definition of a Commemoration ball, but the usual Oxford convention is to refer only to the larger, triennial balls as Commemoration balls. The dress code is usually white tie. Many other colleges hold smaller events during Commemoration Week that they call summer balls or parties rather than Commemoration balls. These are usually held on an annual or irregular basis, and are usually black tie. Merton College holds a triennial winter ball, of which the next will be in 2013.
Recent and upcoming balls
In the past, Commemoration balls were held "night after night"  by different colleges during Commemoration Week. With many colleges now holding smaller annual summer balls, Commemoration balls are now only held by some of the larger colleges, who still follow the traditional triennial cycle. Currently, in each of the first two years of the three-year cycle there is only one Commemoration ball (held by Magdalen College and New College respectively). In the third year there are now four colleges who share this honour (Worcester College, Christ Church, Trinity College,St. John's College).
The 2005 Christ Church Commemoration ball was the first to be held by that college for fifteen years, due to an incident at the 1990 ball that led to the Governing Body suspending the ball and replacing it with an annual summer party until 2005. In 2013 Balliol College held a Commemoration ball to mark the 750th Anniversary of the College's foundation: it was the first Commemoration Ball at Balliol since 1969. Similarly, the commemoration ball hosted by Worcester College on 27th June 2014 was the highlight of celebrations to mark the college's tercentenary.
- 2003 — Magdalen College
- 2004 — New College
- 2005 — Trinity College, Worcester College, Christ Church, St. John's College
- 2006 — Magdalen College
- 2007 — New College
- 2008 — Trinity College, Worcester College, Christ Church, St. John's College
- 2009 — Magdalen College
- 2010 — New College
- 2011 — Trinity College, Worcester College, Christ Church, St. John's College
- 2012 — Magdalen College
- 2013 — New College,Balliol College
- 2014 — Trinity College, Worcester College, Christ Church, St. John's College  Merton  Exeter  Hertford College 
Commemoration ball organising committees generally seek to secure private performances from leading entertainers; some notable performances are listed below.
- The Hoosiers, Pendulum, Eliza And The Bear (St John's College)
- Maxïmo Park, Stornoway with Oxford University Sinfonietta, The Correspondents (Worcester College) 
- Clean Bandit, AlunaGeorge, The Correspondents (Trinity College)
- Athlete, Labrinth, Loick Essien, Natty, Roll Deep (Magdalen College)
- The Feeling (Oriel College)
- The Feeling (St Johns College)
- Mystery Jets (Worcester College)
- The Streets, Sophie Ellis-Bextor (Trinity College)
- Tinchy Stryder (Christ Church)
- The Wombats (Christ Church)
- Sugababes, Stornoway (band) (Trinity College)
- One Night Only, Logistics (Worcester College)
- Balsdon, J.P.V.D.: Oxford Life, page 240. Eyre & Spottiswoode, 1957
- "Merton College Winter Ball".
- Balsdon, J.P.V.D (supra)
- "Balliol 750th Anniversary Commemoration Ball".
- Trinity College Ball http://www.thetrinityball.com/
- Christ Church Commemoration Ball 2014 http://christchurchball.co.uk
- St John's College Ball http://ball.sjc.ox.ac.uk/
- Trinity Commemoration Ball 27th June 2014 Programme
- Athlete at Magdalen College Ball 2012 on Youtube
- Oriel College Ball 2012
- Worcester College Commemoration Ball 2011 :: The Grand Tour
- Trinity Commemoration Ball 2011 :: The Night
- Worcester College Tercentenary Ball - 27 June 2014
- St John's Ball - 27 June 2014
- Hertford Bridge of Sighs Ball - 4 October 2014
- Wadham College Ball - 21 June 2013
- Balliol College Ball - 21 June 2013
- Queen's College Ball - 21 June 2013
- New College Ball - 22 June 2013
- Merton College Winter Ball - 30 November 2013