"Sumer Is Icumen In" is an old English Folk Song which dates from the middle of the 13th Century. The original song was set out as a Rota or Round, where up to 4 voices or groups can enter the song a bar apart. In addition there are 2 further parts or voices who sing a form of ground bass consisting of two alternating bars which are repeated throughout the song. We have a version of Sumer Is Icumen In for six recorders which illustrates this complexity in the original composition, and the original manuscript is held by the British Library. The lyrics are in a dialect of Middle English and the first sentence "Sumer is icumen in, Lhude sing cuccu!" means "Summer has come in, Loudly sing, Cuckoo!". This version is an arrangement of the song for piano, and it is available as Piano Sheet Music, Midi and Mp3 files.
A number of groups, choirs and composers have arranged and performed different versions of this song. Here is one of many versions available on Youtube sung by the Greenleaf Singers. You might remember the mice singing We Will Wash It in Bagpuss. Perhaps the most memorable use of the song is a version called "Sumer Is A-Cumen In" sung at the climax of the 1973 film The Wicker Man. This was arranged by composer Paul Giovanni with words adapted by Peter Shaffer. The song has also appropriately been sung at Beltane events, modern versions of an ancient Gaelic tradition celebrating the coming of summer and usually held in the early hours of 1st May. For more folk songs see our article about Folk Music and Songs with more examples. The video below is a longer version, since it illustrates the melody on 1 instrument before playing it with 4 parts:
Here is a video of Sumer Is Icumen In for piano:
The image below is the first page of the sheet music, and here you can download the full sheet music for Sumer Is Icumen In for piano in PDF format.