For nearly two hundred years, U.S. copyright law has assumed that owners may voluntarily abandon their rights in a work. But scholars have largely ignored copyright abandonment, and case law on the subject is fragmented and inconsistent. As a result, abandonment remains poorly theorized, owners can avail themselves of no reliable mechanism to abandon their works, and the practice remains rare. This Article seeks to bring copyright abandonment out of the shadows, showing that it is a doctrine rich in conceptual, normative, and practical significance. Unlike abandonment of real and chattel property, which imposes significant public costs in exchange for discrete private benefits, copyright abandonment is potentially costly for rights holders but broadly beneficial for society. Nonetheless, rights holders—ranging from lauded filmmakers and photographers to leading museums and everyday creators—make the counterintuitive choice to abandon valuable works. This Article analyzes two previously untapped resources to better understand copyright abandonment. First, we survey four decades of U.S. Copyright Office records, exposing both the motivations for abandonment and the infrequency of the practice. Second, we examine every state and federal copyright abandonment case, a corpus of nearly three hundred decisions. By distilling this body of law, this Article distinguishes abandonment from a set of related doctrines and reveals the major fault lines in judicial application of the abandonment standard. Finally, we highlight the potential of abandonment to further copyright’s constitutional aims by suggesting a series of reforms designed to better align copyright holder incentives with the public good.