Bartók’s major scientific scholarly oeuvre containing more melodies than all his other collections has never been published in English before. The publication of the invaluable historical documentation of around 13500 melodies systematized and supplied with notes has been undertaken in a series. These melodies were classified and annotated by Bartók and partly by Kodály. In this first volume the structure of the system is presented. It contains Bartók’s tabulation of rhythm – a unique constitution in ethnomusicology – a description of his editing concepts, and an extensive study on the evolution of the collection. The book is supplemented with a multifaceted system on indices, and illustrated with facsimile reproductions of transcriptions as well as photographs.