Agricultural markets are characterised by thinner margins, greater price and income volatility. Despite these changes, agricultural raw material markets are increasingly characterised by the vertical co-ordination of farmers and processors. The organisational form of a marketing co-operative is a common means adopted by farmers to achieve this end. In a world increasingly concerned with the importance of the separation of ownership and user, the survival and growth of agricultural co-operatives (in which the primary users of the services are also the main owners) is linked to their economic role, to how members exercise their property rights, and how inputs are used by the co-operative. This paper provides a function that summarises the economic role of agricultural co-operatives and goes on to analyse the contribution to the economic performance of Portuguese wine co-operatives (PWCs) made by the use of property rights, and the skills of the human resources and technology employed. The results of a multinomial logit model show that PWCs would indeed be able to improve their economic performance through the application of integrated management strategies to solve common property and horizon problems, as well as increasing their recruitment of skilled professionals in the areas of management, wine production and marketing, and by the adoption of new technologies of production and packaging.