The collection comprises compositions including orchestral, choral, piano, and chamber works, songs, operas, and the four volume Memorial Edition of Morfydd Owen's posthumously published works.
It also contains a collection of personal memorabilia - programmes, images, her marriage certificate, a letter, and a large collection of press notices.
Also included are several older catalogues of the collection, as it passed through the hands of University College Cardiff, then the Welsh Music Information Centre, then finally Special Collections and Archives.
A list of Morfydd Owen material available at the National Library of Wales is also provided.