Of all the musical developments of rock in the 1960s, one in particular fundamentally changed the music's structure and listening experience: the incorporation of extended improvisation into live performances. While many bands-including Cream, Pink Floyd, and the Velvet Underground-stretched out their songs with improvisations, no band was more identified with the practice than the Grateful Dead. In Michael Kaler examines how the Dead's dedication to improvisation stemmed from their belief that playing in this manner enabled them to touch upon transcendence. Drawing on band testimonials and analyses of early recordings, Kaler traces how the Dead developed an approach to playing music that they believed would facilitate their spiritual goals. He focuses on the band's early years, the significance of their playing Ken Kesey's Acid Test parties, and their evolving exploration of the myriad musical and spiritual possibilities that extended improvisation afforded. Kaler demonstrates that the Grateful Dead developed a radical new way of playing rock music as a means to unleash the spiritual and transformative potential of their music.