Chapter 4. Economics of Common Property Management Regimes The purpose of this chapter is to identify the reasons for collective action failures and successes in natural resource management and to understand in the light of economic theory the mode of operation of the factors involved whenever possible. In the first section we clarify the notion of a common property management regime and provide cautionary remarks about estimation methodologies commonly used. In Section 2 we focus on the general case where common property regulation is feasible yet only if governance costs are kept to a reasonable level. Emphasis is placed on such factors as the size of the user group income or wealth inequality and availability of exit opportunities. Special attention is paid to the aspect of inequality since this has remained a rather confused issue in much of the empirical literature. Economic theory can contribute significantly to improving our understanding of the manner in which it bears upon collective action. In Section 3 we discuss cognitive problems as an important impediment to the design and implementation of efficient common property management systems. We also present evidence of the deleterious effects resulting from the absence or inappropriateness of state interventions particularly where they are motivated by private interests. In Section 4 the importance under a co management approach of appropriate incentive systems at both the village and state levels is underlined and illustrated.