People in a rural white working-class music scene in the southeastern United States frequently labeled themselves and others as certain kinds of people, in categories like age, gender, class, race, kinship, and more. This socially generative practice—the explicit recognition of categorical group difference and sameness—was a frequent point of friction with white middle-class musicians from a nearby city who rejected being “fenced in” by such labels. With few exceptions, these musicians found the imposition of categories of commonality or difference between people to be generally uncomfortable and problematic in social interaction, preferring to emphasize the unique and agentive aspects of their lives. This conflict reveals an area of underappreciated and persistent class conflict—“ideologies of categorization”—here constituting a politically meaningful internal division in whiteness. I explain this conflict and examine its profound implications for academic theory and for a class-aware leftist identity politics.