The participation of small scale fishers in institutional management of tropical coastal marine fisheries activities has long been excluded, notably in the centralized states of Central America. The major objective of this study was to determine the potential of co-management of coastal marine small scale fisheries activities in Golfo Dulce (South Pacific of Costa Rica). The study consists of two main parts. The first analyses the management of small scale fishing activities exploiting coastal marine resources in tropical developing countries, and the second is devoted to the case study of Golfo Dulce. In a first step, the Costa Rican small scale fishery sector was characterized, especially its historical evolution and its decentralized and multi-agency management. The various modalities of the participation of small scale fishers in its management were illustrated by several case studies (Cahuita, Marino-Ballena, Palito, Tárcoles, Golfo Dulce). Second, fishing practices and socio-economic profile of small scale fishers of the three communities of Bahía Pavones (southeast of Golfo Dulce) were characterized. The small scale fishing activity is essentially based on eight species, of which the two main ones, Lutjanus gutattus (spotted rose snapper) and L. peru (Pacific red snapper) could be overexploited. The participation of small scale fishers to local organizations is significant despite a general lack of confidence towards these organizations. Finally, comparing the different case studies revealed the existence of eight key conditions for the development of a successful co-managed small scale fishery in Costa Rica. Within the Marine Responsible Fishing Area of the Golfo Dulce, it is the manipulation of small scale fishers by various user groups (in particular government and the tourism sector) that hinders the process of co-management.