It interprets the term in the widest possible sense, and always tries to include rather than exclude material. Items are collected if they could be considered traditional in any way – in origin, or in idiom, or in transmission or style of performance, etc. – or if they are relevant to an understanding of traditional music and its contexts.

As well therefore as collecting music and song that is known to be centuries old, the Archive also collects reels and jigs lately composed and recent ballads in traditional style. Its holdings contain the sean-nós singer and the solo fiddle player, along with heavy-metal groups playing hornpipes and symphony orchestras performing arrangements of traditional airs. Printed collections of tunes and songs keep company with dissertations on traditional music and handbooks of ethnomusicology. Images range from ballad-sheet woodcuts to downloaded digital photographs.

Traditional music is regarded by the Archive as being simultaneously a vigorous element of contemporary Irish culture, one which enjoys widespread popularity even outside Ireland, and a valuable part of historic Irish culture. It therefore emphasises the on-going collection of modern publications in Irish traditional music – in audio, printed and visual forms – and live field-collection, as well as assembling classic and little-known historical documents of the music.