This dissertation represents the first study of indie classical, a significant subset of new music in the twenty-first century United States. The definition of “indie classical” has been a point of controversy among musicians: I thus examine the phrase in its multiplicity, providing a framework to understand its many meanings and practices. Indie classical offers a lens through which to study the social: the web of relations through which new music is structured, comprised in a heterogeneous array of actors, from composers and performers to journalists and publicists to blog posts and music venues. This study reveals the mechanisms through which a musical movement establishes itself in American cultural life; demonstrates how intermediaries such as performers, administrators, critics, and publicists fundamentally shape artistic discourses; and offers a model for analyzing institutional identity and understanding the essential role of institutions in new music. Three chapters each consider indie classical through a different set of practices: as a young generation of musicians that constructed itself in shared institutional backgrounds and performative acts of grouping; as an identity for New Amsterdam Records that powerfully shaped the record label’s music and its dissemination; and as a collaboration between the ensemble yMusic and Duke University that sheds light on the twenty-first century status of the new-music ensemble and the composition PhD program. Combining archival and digital research, reception history, interviews, and fieldwork, I uncover the flows of cultural and economic capital that govern how classical and new music operate in the present day.