Costa Rica is internationally recognized for its management of its protected areas. With its high biological diversity, this country has positioned conservation as a pillar of its development. During the last decade, the government has stimulated a process of modernization of the National System of Protected Areas (SINAC). The creation of Conservation Areas, as territorial units for the management of resources, has permitted the establishment of conservation programs reaching beyond the limits of protected areas. The new system gives an excellent opportunity for development of ecotourism, which in many cases is a basic economic alternative for local communities. This paper focuses at showing the influence of ecological tourism on the activity of populations adjacent to the protected areas. It was written on the basis of the literature as well as studies and observations conducted during the visit in Costa Rica in 1999, primarily within the national parks.