Subculture research on alternative sports has focused on the seemingly inevitable commodification and media co-option of these activities and their internal status hierarchies. In this article, I examine the neglected issue of how participants define the informal “rules” of a self-governed sport. Specifically, I am interested in intragroup conflict among long-time traditional rock climbers over the legitimacy of practices that reduce risk. I spent sixteen months conducting participant observation in multiple locations in the rock climbing world, collected seventeen in-depth interviews, and consulted a wide range of secondary material. Drawing on social worlds theory to analyze the sociohistorical sources of competing ideologies, the participants’ claimsmaking activities, and their strategic actions to maintain and challenge informal rules, I provide a more nuanced and complex picture of social change in alternative sports. I also demonstrate the value of the social worlds perspective for understanding the interactive construction of social worlds and participants in constant flux.