Justifications for regulation are commonly based on the identification of market failures. This is however inadequate to account for much regulation, and sees regulation as inherently second best to market allocations. This article argues that, although some regulation will be based on market failure, other justifications can be found in the protection of rights and in the maintenance of social solidarity. Theoretical support for this last rationale can be found in the work of Durkheim and Duguit and the concept of public service. To accept this rationale for regulation has important implications both for regulatory policies and regulatory instruments.