This book provides the first detailed reception history of adaptations of Johann Sebastian Bach's Aria mit 30 Veränderungen (Goldberg Variations, BWV 988). It documents multiple ways Bach's work has appeared in arrangements, transcriptions, and re-compositions from 1800 to 2020. It examines adaptations for the traditional concert hall as well as for dance, theater, cinema, literature, digital media, and visual art. Overall, the book reveals a dramatic increase in adaptations of the piece in the late twentieth and early twenty-first centuries. In addition, it brings the reception history of Bach's Goldberg Variations into dialogue with broader scholarly discourse about performance practice issues. The piece was often performed in transcribed or arranged versions in the nineteenth century and then again in the late twentieth and early twenty-first centuries. Yet if nineteenth-century adaptations of this piece were usually created out of necessity, as a means of performing a lengthy piece without access to the original instrument, many twenty-first century adaptations, which have developed alongside historically informed performances, were motivated by deconstructionist ideologies. This contrasts with the middle part of the twentieth century, when there was a prevalence of historically informed performances and a dearth of adaptations. Comparisons to other works by Bach reveal similar performance practice trends. The reception history documented in the book also considers the musical work concept. It shows that, particularly since the late 1980s, there has been a loosening of the regulative hold of the modernist work concept associated with single authorship, structural unity, and an autonomous score. It reveals that many recent adaptations are not direct interpretations of an authoritative text, but engage in multivalent dialogues as Bach's score becomes an infinite or open text in which multiple people, including subsequent (re)-composers, performers, directors, and audience members enter into inter- and intra-textual conversations. In the process, the book contributes to recent studies about adaptations, the role of musical authorship, and changing notions of Bach and the work concept in the twenty-first century. At the same time, it discusses many recently composed pieces, including ones by underrepresented composers.