This paper explores the complex role that brand names have played in the maintenance of therapeutic standards within twentieth-century American medicine. What made a generic drug generic in the second half of the twentieth century--and by extension, what made a nonproprietary drug not proprietary in the first half--was dependent on changing drug branding practices and evolving standards of evidence attached to claims of therapeutic efficacy and safety. This article maps three eras of shifting oppositions between branded and unbranded pharmaceuticals. First, an era of "ethical marketing," extending from before the Pure Food and Drug Act of 1906 into roughly the 1930s, which pitted nonproprietary or "ethical" pharmaceuticals against proprietary or patent medicines; second, an era of ascendant brand-name prescribing from the 1930s until roughly the 1960s, as manufacturers of innovative and patent-protected "specialty" drugs depicted generic production as a form of counterfeiting; and finally, an era of generic backlash from the 1960s onwards, which assumed the interchangeability of branded and generic drugs. This article uses clinical, popular, policy, and trade literatures to explore the enduring roles of brand-logic in the face of generic competition in the American drug market.