This book contains a musicological refl ection on a body of music theory covering the second half of the twentieth century, early beginnings and late developments included. Few musicologists have concerned themselves with pitch-class set theory. This is not surprising. Pitch-class set theory is a product of music theory's remarkable rise (or renaissance) as an independent academic discipline in the United States—independent, that is, from musicology. A theory of pitch relations in post-tonal music, it has chimed in with a deep interest in matters of musical structure shown by composers and music theorists. And as far as the study of musical works from the past is concerned, it has viewed the score as its primary source of information. This goes against the grain of the musicologist who, instead of isolating music, seeks to place it in a larger context—social, cultural, historical, or otherwise.

However, I see no reason why this musicologist should avoid dealing with pitch-class set theory altogether. Although it has developed into a highly distinct area of competence, it is part of the cultural environment in which music is made, heard, and studied. It has provided a vocabulary for the description of western art music from beyond the common practice period. It has established an image of this music as being tightly, though not always conspicuously, structured, opening new avenues for analytical practice. Today, it is taught at colleges and universities, and it is amply represented in the music literature. Seen thus, pitch-class theory defi nitely falls within the scope of a contextualist approach to music. By addressing its history, taking into account the variety of factors that contributed to its development, this study aims to establish a new rapport between musicology and music theory. As a consequence, the reader will find historical narrative side by side—and sometimes inextricably entwined—with theoretical and analytical discourse. It is my hope that this combination of perspectives will be to the enrichment of them both.