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 2016.
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 held by only some of the larger colleges, who still follow the traditional triennial cycle. Oriel College hosts a ball in the first year of the three-year cycle, and until recently Magdalen College also did. However Magdalen College cancelled their ball in 2015 at the last minute downgrading to a smaller affair. Currently, in the second year, there is only one regular Commemoration ball held by New College. In the third year, there are now four colleges with this honour (Worcester College, Christ Church, Trinity College, St. John's College).