This article introduces a preliminary model that conceptualizes the drivers, expressions, and consequences of consumers' controversies about the limits of legitimate consumption within a social context. Drawing on qualitative data on the North American conflict over the cultural legitimacy of the Hummer brand of vehicles, the study documents that -contrary to the prevailing consumer-producer centric model -market-mediated social conflicts also emerge as immediate, interpersonal social practices through which consumers contest each others' consumption choices, ideologies, and behaviors. The study reveals that consumer controversies often begin with violations of social expectations, manifest in vigilant justice, insult, discredit, ridicule, and instruction practices, and serve consumers to preserve, promote, and defend the consumption-related meanings, practices, objects, and identities that they consider sacrosanct for themselves and their social peers. The study suggests that consumer controversies affect consumer culture, identity projects, and marketing practices in important ways previously unrecognized by theories of consumer emancipation and resistance.