Fraud jurisprudence in the federal Trademark Office encourages trademark holders to remain ignorant-or worse, silent-regarding facts that may reveal the generic or functional nature of their marks. If that failure to investigate or to voluntarily disclose relevant information results in the award or maintenance of afederal trademark registrationfo r invalids ubject matter, the public suffers an injury. The injury is particularly acute because numerous amendments to the 1946 Lanham Act in the decades since its passage have substantially increased the evidentiary utility and power of a federal registration. Although Procedures exist to allow a challenger to oppose or cancel an improvidently granted registration, unless and until a successful challenge is mounted, the registration effectively cordons off matter as proprietary that properly should inhabit the public domain. This Article urges imposition of a duty of disclosure in the Trademark Office which could be enforced upon a showing that the applicant or registrant failed to conduct a reasonable investigation for facts related to genericism or functionality and to disclose the same to the Trademark Office. The proposed duty would require amendment of the Lanham Act as it would shift the burdens of production and proof on the issues of genericism and functionality from the Trademark Office to the applicant; it would persist throughout the life of any resulting registration requiring correction of the record should facts related to those issues arise. The remedy for failure to comply with an affirmative duty of disclosure would be a refusal to issue a registration or cancellation of the relevant part of any existing registration. The move away from a fraud standard toward an affirmative duty of disclosure in the Trademark Office would promote fair dealing with a government agency, would not burden holders of valid trademark rights unduly, and would preserve the public domain.