Sociological interest in nonsuicidal self-injury is over 20 years old, and the last decade shows a marked increase in journal articles and research monographs. Here, we survey and critically evaluate this growing sociology of self-injury, providing a short history of its development, and describing the focus of four contrasting approaches used in exploring a sociology of such a private practice: institutional interactions; processes of social construal and construction; the social in the lived experience of subjects; and the role of social relations and communication. We argue that these approaches in the sociology of self-injury more generally represent four broader social theoretical perspectives on how the personal is always-already social. Understanding this connection between the empirical search for the social in self-injury, and theoretical conceptualizations of the social in the personal, is key to opening up the future of the sociology of self-injury, and appreciating what it has to offer sociology more generally. The more we understand what is social in self-injury, the more we will understand how the personal is always-already social; and the greater the theoretical investment in our methodological apparatus, the more we will be able to detect and comprehend the social dimension of this intensely personal practice.