The practical importance of intangible personalty such as debt, bonds, equities, futures, derivatives and other financial instruments has never been greater than it is today. The same may be said of interests in intellectual property. Yet the assignment of these intangible assets from one to another remains difficult to understand. Assignments are often taken to operate as a form of transfer akin to conveyances of legal titles to tangible personalty. However, this conception does not accurately reflect the law of assignment as it has developed in the caselaw in England and Wales. This book sets out a different model of the workings of assignments as a matter of English law, one that provides an analytical, yet historically sensitive, framework which allows us to better understand how, and why, assignments work in the way the cases tell us they do.