Book excerpt: Toward a Sociology of Music Therapy: Musicking as a Cultural Immunogen addresses how music therapy may expand its theoretical foundation toward sociology in order to meet some of the major health challenges in contemporary societies. Building upon post-structural and posthumanist thinking, this book advocates a new understanding of the discipline of music therapy, as well as outlines major areas of practice that can extend music therapy services into public health.The concept of "music as a cultural immunogen" is illustrated through research interviews, field work, and cases taken from the media, demonstrating how various forms of "health musicking" help regulate emotions, build sustainable musical communities, and install meaning, hope, and a sense of existential "resonance" in life.Also discussed are issues from the sociology of profession as related to the identity of the music therapist. Other topics are ontologies of music, conceptions of health, holism and disability, as well as different ideological stances among leading pioneering music therapists in the previous century, like Christoph Schwabe, E. Th. Gaston, and Nordoff and Robbins.