Abstract: Due to a variety of factors, Intellectual Property rights are expanding and, as a result, overlapping more than ever before. This phenomenon poses a wide array of problems and challenges to a system which was initially devised as comprising a set of isolated compartments, each with its defined purpose, object, and specific set of rules. As no careful thought on the interaction of these rights in cases of overlapping protection seems to have been given by the legislators yet, the solutions to the arising questions are far from obvious or established.Among the diverging rules between IPRs the ones concerning ownership and entitlement can easily lead to situations where different rights on the same object are owned by different persons. Thus the question emerges: what happens when two (or more) different people own different rights whose object is the same? How to solve the situation where objective cumulation is not mirrored by subjective cumulation? If a professor creates an original database and is accordingly entitled to copyright and, her employer, the University has put substantial investment in its creation, owning the sui generis right therein, how can exploitation occur? What rules regulate the conflict between the creator of a logo and the company that registers and uses it as a trade mark? These questions are analysed under European law, focusing on the existing corpus of EU primary and secondary legislation and jurisprudence. When the EU body of law provides no guidance or a national example is required, that analysis focuses on three countries: Germany, France and the UK, other jurisdictions being also considered.The book starts by describing the occurrence of overlaps and the dangers deriving from split ownership. A study of the diverging rules of copyright ownership is necessary in order to define some operative concepts. The issue is then considered in five specific cases of overlapping protection: trade marks and designs, trade marks and copyright, designs and copyright, database sui generis right and copyright and, finally, copyright and patents in the field of computer programs.From the analysis of these cases some conclusion are drawn regarding the way legal rules answer to the split ownership problem and to what extent the existing approach is commendable.The book ponders and suggests some solutions to the problem, namely the convergence of ownership rules, the avoidance of overlaps tout court, the prevalence of the closest regime, abuse of rights, implied licences, and expanding copyright solutions by analogy. It is suggested that the latter is the best approach even though a combination of some of the mechanisms described is to be expected. It concludes by considering possible legislative intervention and the form it might take.