Stigma is a concept that marketers frequently and casually use, but it is underexplored as a theoretical construct. The authors propose a theory of stigma that identifies it as a formative construct associated with perceptions of deviance and undesirability along with inflated risk perceptions. This research also goes beyond the social stigma typically studied in marketing and related fields to examine product stigma. Specifically, this research explores the stigmatizing effects of labeling on genetically modified foods, a domain of economic and political importance. Using different labels proposed in international debates, the experiment reveals that such labels can create stigma and that, to some degree, marketers can attenuate stigma through certain qualified labeling.