In this paper we are concerned with private sector participation in natural resource management in developing countries. The paper addresses both the establishment (or formalisation) of private property rights to natural resources, and the private markets in which such rights are exchanged. The paper examines a number of different natural resources: irrigation water, potable water, fisheries, and forest land. It is argued that private sector participation in natural resource management has the potential to secure significant environmental benefits, but that the optimal form which such participation takes is dependent upon the characteristics of the resource in question. Irrespective of the resource and the form of private sector participation adopted, regulatory capacity is key to securing public environmental benefits.