Outsider music is that which exhibits an aspect of practice that is irreconcilable with conventional notions of musical tradition, musical style and, particularly, musical competence. This chapter investigates outsider musicians that have apparent connections to rock practice in that they make use of rock instrumentation and other aspects of rock’s musical style. It is not a contradiction to call these artists outsiders if they incorporate aspects of rock into their practice – they still may not treat these aspects in a way that gels with expectations of the style, or expectations of musical competence. Outsider musicians are often accorded a particular authenticity where value is found in music beyond the parameters of structural cohesion or finished product. They are often linked with a social marginality that is the result of, at one end of the spectrum, a lack of interpersonal skills, and at the other, mental illness. Although the idea of primitivism is associated with much of the music covered in this book, outsider music makes a particular claim to it. Whether coming from the drug-damaged minds of Alexander ‘Skip’ Spence or Syd Barrett, the virtual social experiments of The Shaggs and Captain Beefheart & His Magic Band, or the unknowable minds behind Jandek and The Residents, this music may be received as coming from beyond the experience of, or situation in, rational, adult society. The corresponding assumption is that a certain kind of truth may emerge that is not accessible to those of us entirely immersed in, and compromised by, ‘normality’.