Copyright law’s constitutional mandate is to advance artistic progress for the public good by granting authors a set of exclusive rights. When considered in the context of creative endeavors that build upon preexisting, already copyrighted works, however, this seemingly straightforward objective becomes more complicated: in this situation, the law must balance the incentive to prepare the initial work with the incentive for improvement and continued progress in the form of derivative works, which can be inhibited by the rights conferred on the author of the preexisting work. Indeed, allowing individuals broad rights to exclude the public, for the benefit of the public, presents a contradiction in intellectual property law when those individual rights are invoked to prohibit absolutely the production of derivative works, as some courts have permitted copyright litigants to do. A blocking copyrights doctrine would help to relieve that uneasy and unnecessary result. Such a doctrine would be similar to the well-established blocking patents approach to overlapping inventions in intellectual property law, and would allow an unauthorized improver of a preexisting copyrighted work to practice, and retain rights to, the original contributions in her derivative work, subject to compensation for use of the preexisting work. In addition to looking to patent law for guidance, the law relating to improvers of tangible property is also instructive in addressing the dilemma of unauthorized derivative authors in the copyright system: that body of law offers even greater acceptance and encouragement of the efforts of subsequent users of property. Although copyright law, when compared to both patent law and the law of tangible property, presents equally, if not more, compelling reasons for granting an improver relief, a blocking doctrine has not been accepted by the courts in the copyright context. As this Article demonstrates, courts’ failure to accept the doctrine is in part due to a misunderstanding of the statutory provisions governing derivative works. In addition to correcting this misunderstanding, the Article points to recent decisions relating to remedies in copyright cases that further open the door to implementation of a doctrine of blocking copyrights. Taking this