I attempt in this paper to develop a theory of paternalism which indicates when and why a paternalistic action is justified. In the first two chapters I consider the extant theories on this subject: in the first chapter I develop a utilitarian theory of the justification of paternalistic interference, and in the second chapter I consider various non-utilitarian theories that have been offered. Although I do not agree with the utilitarian analysis of rights, and so with their rationale for paternalistic intervention, I argue that such a theory does provide a strong presumption against such interference. Nor do I find any of the non-utilitarian theories satisfactory, although they each contain certain important insights. In the third chapt...