Throughout the twentieth century, literary theorists developed a range of new techniques to analyze written works. In addition to studying a work’s text, analysts became increasingly interested in studying a work’s intertext, that is, its relationships to other texts. Intertextual approaches to music analysis have remained somewhat uncommon, although some commentators, including Christopher Reynolds and Michael Klein, have used intertextual analysis alongside more traditional musical analytical techniques such as Schenkerian analysis or pitch-class set theory. This dissertation applies the notion of intertextuality to the analysis of popular music written after about 1965, focusing in particular on examples that are connected to both classical and popular traditions of Western music. This dissertation explores how the creators of pop and rock music became increasingly interested in incorporating art music traditions into their own works, particularly during the fifty-year period from 1965 to 2015. Chapter 1 provides a brief historical introduction to musical intertextuality, concentrating broadly on Western art music from the medieval period up to about 1965. Both in Chapter 1 and throughout the dissertation as a whole, a small number of examples illustrate central concepts; the coverage makes no attempt to be comprehensive. Chapter 1 also introduces literary theories surrounding intertextuality that are applied throughout the later chapters. After the first chapter, Chapters 2 through 4 follow in approximately chronological order and approach the topic of musical intertextuality from three different points of origin: a genre, a source, and a composer. The genre is progressive rock, the subject of Chapter 2. Progressive rock artists such as Emerson, Lake, and Palmer created new works that were connected by various means to classical precedents. Examples are chosen from about 1965 to about 1980. The source is Johann Sebastian Bach, whose music is one of the major nexus points for musical intertextuality in many styles. In addition to serving as a source for many progressive rock artists in the 1960s and ’70s (discussed in Chapter 2), Bach’s music has continued to have a generative function for musicians at the turn of the twenty-first century. Chapter 3 examines three contrasting examples: Tenacious D, Stuart Davis, and Chris Thile. The composer is Rivers Cuomo of Weezer, whose music contains numerous allusions to both popular and classical sources. Drawing on examples from 1994 to 2016, Chapter 4 examines connections between the music of Weezer and that of Johannes Brahms, Aaron Copland, and Giacomo Puccini, among others, arguing that intertextuality is a central characteristic of Weezer’s music.