One of the most pressing problems now facing commercial lawyers is to explain the principles which determine when a remedy is proprietary and when it is not. This book provides a broad overview of the subject. It examines representative business transactions which commonly give rise to legalor equitable interests in personal property. Its aim is to distil the fundamental principles understanding the relevant legal analyses. The result is to provide a more theoretically rigorous analytical framework for proprietary interests in personal property. The practical advantages of this arepotentially twofold: new commercial transactions can be more effectively structured; in addtion, disputes between contracting parties can be more reliably resolved. Two features of the analysis are significant. The first is the elastic nature of proprietary interests in personal property. Althoughproprietary interests can be broadly classified as ownership or security interests, these are relative concepts which may be affected significantly by impinging contractual arrangements. The second feature is the necessary and intimate integration of law and equity. Equitable proprietary interestsare remarkabldy prevalent; this prevalence is directly related to the apparent ease with which equity is able to convert particular personal obligations into proprietary interests.