Though popular music in the twentieth century was often disseminated aurally through recordings, transcribers have reified these sounds into musical notation to aid in analysis and re-performance. Today, musicians use myriad types of transcriptions—online tabs, lead sheets, and note-for-note sheet music—to help them understand and learn their favorite songs. This dissertation narrates the emergence of these transcriptions among different genres during the Rock Era, a period stretching from the late 1950s through the late 1970s. Detailed transcriptions were far less common then than now: some were created to secure copyright protection, while others helped musicians gain competency in a certain performance style. By the 1980s, however, many transcriptions started being published as exquisitely crafted musical works that could stand in for their model—the recording. I argue that these documents are most often influenced by classical music aesthetics, as transcribers borrow from this tradition to legitimize popular music at a time when it remained outside the purview of the musical academy. In Chapter 1, I explore the ontology of musical transcriptions, focusing particularly on the relationship between transcriptions and musical works in the genres I study in subsequent chapters: jazz, the blues, and rock. Chapter 2 studies Gunther Schuller’s transcriptions of Ornette Coleman’s free jazz; one example translates Coleman’s improvisation into a “coherent” musical artifact, elevating him to Western art music standards and problematically occluding other musical inheritances. Chapter 3 provides an overview of the different varieties of guitar transcriptions in this era; I profile key blues guitar pedagogues and transcribers, Happy Traum and Stefan Grossman, and then scrutinize various publications of Jimi Hendrix’s guitar music. I examine The Frank Zappa Guitar Book in Chapter 4, a collection of exceptionally detailed (and overly complex) transcriptions of Zappa’s guitar improvisations undertaken by young Steve Vai that serve to impart a sheen of legitimacy on Zappa’s music, aligning his improvised compositions with his written ones. My conclusion explains the proliferation of note-for-note transcriptions at the end of the 1980s, a trend that stems from the popularity of neoclassical metal and the emerging treatment of canonic rock music as “generational objects.”