Résumé
This article assesses, from an institutional point of view, the performance of the Costa Rican Payment for Environmental Services Program (PESP) as a conservation tool focusing on its main modality: the forest protection. The PESP has had a low direct impact on the forest cover of the country but may have had an important indirect impact as it served as compensation for the prohibition of forested land uses change. This program appeared also quite competitive from the point of view of its costs before the institutional transformation that occurred in 2008. The PESP has also proved to be a very effective fundraising tool, but it has failed in the development of strong synergies with other institutions for forest protection and it has not supported the development of sustainable forest management. From a cosean perspective, a significant potential for improvement of the PESP cost-effectiveness exists on the short term through changes in the program's rules. However, these changes often deny the program's institutional nature and could jeopardize the program effects on the long term. A safer way to improve the PESP performance is to focus on strengthening its management and governance.