The All-Ireland Under-21 Football Championship (known for sponsorship reasons as the Cadbury Under-21 Football Championship) is the premier "knockout" competition for players aged between 18 and 21 in the game of Gaelic football played in Ireland. The series of games are organised by the Gaelic Athletic Association and are played during the summer months. Dublin are the current All Ireland U-21 Champions, having defeated Roscommon in the final for the second time in three years. The prize for the winning team is the Clarke Cup, which is named in honour of former Kildare Secretary and Treasurer Tim Clarke.
The All-Ireland Under-21 Football Championship was created in 1964 in response to a Congress motion put forward by the Kerry County Board. Since then the competition has grown in importance and profile. The championship is run on an inter-county provincial basis with the winners from Munster, Leinster, Ulster and Connacht playing off against each other in two semi-finals. Cork are the most successful teams in the history of the Under-21 Championship. Two teams have achieved three-in-a-rows; Kerry from 1975 to 1977 and Cork from 1984 to 1986. The coveted treble of winning senior, under-21, minor titles in the same year has been achieved on just one occasion, by Kerry in 1975. Because teams will only play together for at most, about two or three years, unlike the senior competition, it is unusual that one county will dominate for periods any longer than this.
It is usually considered a mark of a very promising player to play for both a county's Under 21 and Senior team at the same time. Many great players have achieved this, although one particular example would be Frank McGuigan, who, in 1973, represented Tyrone in the Ulster Finals of the Minors, Seniors and Under 21s.
In May 2011, Galway won the 2011 All-Ireland Under 21 Football Championship after a 2-16 to 1-9 against Cavan at Croke Park.