Third-party certifications on product labels play the role of verifying producers’ compliance with certain objective production standards that cannot be directly observed by consumers. Third-party can provide a way of mitigating some of the information asymmetries that naturally arise between informed producers and uninformed consumers. Certifications thus transform some of a product’s “credence attributes”—which require consumers to trust producers’ claims that they cannot verify themselves, such as organic farming methods (Darby & Karni, 1973) —into objectively verified, observable search attributes that consumers can rely on when making purchase decisions. In the wine market, natural wine is an increasingly popular category, but one that is hard to identify. In accordance with legal constraints, the majority of products do not display the term “natural wine” on their labels. Additionally, in contrast to the labeling conventions observed for organic and biodynamic wines, natural wines are not typically identified through the use of third-party certifications. Instead, natural wine’s credence attributes must be signaled by other means. To explore the dynamics of market signaling in natural wine, we conducted semi-structured interviews with 55 natural wine producers from five European countries. Our findings reveal significant differences between producers in how they define natural wine, indicating that the category, unlike the organic and biodynamic categories, exhibits fuzzy technical boundaries. For a deeper understanding of the category’s market boundaries, we propose a comparison between how the natural wine and craft beer categories are signaled. Two distinct attributes emerge as particularly salient signals in the identification and marketing of natural wine: authenticity and oppositional identity.