The co-operative mode of organization has been regarded as the ideal way to solve problems of coordination and management within the fisheries, at least from the fishermen's point of view. By taking control over processing, marketing and sometimes financing, fishermen hoped to break the relation with private fish-buyers and merchants, thereby freeing themselves from exploitation and external control. Fishery co-operatives have been established in western industrialized countries, often in competition with a private, capitalist sector. They have also been a common device to organize fishermen for economic and social development in Third World Countries. This paper addresses the lessons which can be drawn from the experiences of cooperatives in various fisheries. The results are not particularly encouraging. We discuss some of the problems and obstacles confronting co-operatives, and what can be learned from the failures as well as the successes. In particular we focus upon problems concerning the formation of fisheries co-ops, the relation between a fisheries co-op sector and state government, the capital accumulation process within the co-op, conflicts of interest between participant members, consequences of being multi-purpose organizations, and, finally, the function of management in a fisheries co-operative. The main conclusion is that one should have a flexible attitude to co-operative principles instead of implementing a fixed, pre-defined organizational model. Fruitful co-operation among fisheries people can be organized in many ways and not necessarily within the framework of co-operative.