AbstractThe Reykjavik Conference on 'Sustainable Fisheries in the Marine Ecosystem' in 2001, and the commitment made by FAO members in the Reykjavik Declaration to responsible and sustainable fisheries in the marine ecosystem, strengthened and legitimized the ecosystem approach to fisheries (EAF) as the reference framework for managing the fishery sector. This direction was further reinforced by the World Summit on Sustainable Development (WSSD) (Johannesburg, 2002) that recommended the implementation of an ecosystem approach to aquatic resources management by 2010. The requirements implicit in the EAF, such as addressing more complex and poorly understood systems and the associated uncertainty, increasing data requirements, consideration of several timescales, and the recognition of the importance for a broader stakeholder participation at various stages of the fisheries management process, have initially intimidated many and fostered a perception of the EAF as a difficult and perhaps impossible task. Furthermore, the understanding of the basic principles of what an ecosystem approach actually implies are still not always understood or agreed upon. Attitudes are however changing, both at the international and at the national levels, and a pragmatic approach has been adopted in many places to see how conventional fisheries management can be improved to incorporate ecosystem considerations and more properly deal with the social dimension. While it could be argued that a large proportion of FAO's work is either directly or indirectly promoting the application of an ecosystem approach, FAO has also specifically addressed EAF by developing guidelines for its implementation, following the mandate issued in connection with the Reykjavik Conference. Promotion has been conducted in a number of conferences, regional and national initiatives have been monitored informally and specific case studies have been implemented through field projects. This contribution will summarize the developments in the conceptual framework that have taken place in FAO since the Reykjavik Conference, and try to put emphasis on the basic principles that should underpin the application of the EAF. Despite the progress made, important challenges still need to be faced. These are not only related to the direct drivers of marine ecosystem change, such as fisheries and other sectors utilizing goods and services from the marine ecosystem, but also related to the indirect drivers such as changes in human population coupled with a widespread aspiration for an improved standard of living, and global economic policies.