Kanuragan is a secret ritual initiation tied to local cosmological practices and cults used by the Javanese as a source of self-help on issues related to health, welfare, and protection. At basic levels, the practitioners of kanuragan use special entities called aji to gain strength and invulnerability. At the next level, the teaching of the master involves a specific mystical knowledge tied to the acquisition of spiritual authority. This article describes the process of transmission, the persons involved, and the role that kanuragan plays in Javanese society for security purposes and in warfare. The analysis shows how kanuragan competes with new secular and religious systems of value as well as with sorcery and new embodied practices such as sports competitions, to provide comparative insights on the formation of social categories.