The third volume in the Complete Edition contains Bartók's works for piano solo composed between 1914 and 1920. Bartók's pianistic oeuvre from the years of World War I span a broadly varied spectrum; in addition to simple arrangements of folk music (15 Hungarian Peasant Songs, Sonatina) and original pieces for the concert podium (Suite, op. 14), we find Bartók's audaciously innovative Etudes (op. 18) inspired by Liszt, as well as Improvisations (op. 20), perhaps his most abstract and original folk music adaptations.

The appendix of the volume reproduces movements originally intended for, but eventually discarded from, Suite and 15 Hungarian Peasant Songs, as well as all original sources for the folk-inspired pieces. The introductory essays in English, Hungarian, and German not only explore the genesis and reception of the works more thoroughly than ever before, but also orient the reader in issues of notation and performance. The critical commentary presents all manuscript and print sources of the works in detail (including folk music sources), it documents the compositional processes and surveys the range of textual variants and problems.