Tonality – or the feeling of key in music – achieved crisp theoretical definition in the early 20th century, even as the musical avant-garde pronounced it obsolete. The notion of a general collapse or loss of tonality, ca. 1910, remains influential within music historiography, and yet the textbook narrative sits uneasily with a continued flourishing of tonal music throughout the past century. Tonality, from an early 21st-century perspective, never did fade from cultural attention; but it remains a prismatic formation, defined as much by ideological-cultural valences as by its role in technical understandings of musical practice. Tonality 1900–1950: Concept and Practice brings together new essays by 15 leading American and European scholars.