Ecotourism has often been praised as an ideal opportunity to protect natural resources while providing an economic alternative to the local population. On the other hand, however, some authors have severely criticised ecotourism or even declared it to be a failed concept. The analysis of three private and three community-based ecotourism enterprises in the Mexican biosphere reserve Los Tuxtlas with regard to their contribution to the region?s sustainable development has produced a diverse impression. In all the enterprises there are aspects concerning the ecological sustainability which could be still improved. At the same time, various factors constrain the economic success of ecotourism in the region. Thereby also its potentially positive social and ecological effects are limited. Actually, these benefits of ecotourism can be found in Los Tuxtlas, but they seem to be rather restricted to the local level, though not really significantly regarding the whole region. Nevertheless, the potential to enhance the successes of ecotourism in the region are high, for instance through a better coordination of the institutions which are supporting ecotourism, as well as through an enhanced cooperation among the ecotourism enterprises. As was figured out by this study, the most important contribution of ecotourism in the region?s sustainable development process is environmental education. Among the members of the ecotourism projects a high awareness of the value of the unique natural landscape of Los Tuxtlas could be observed. Partly, this awareness is already passed on to visitors as well as to the inhabitants of the region, especially to school children. However, there is still need for more sensitisation. It will be interesting to observe if in future ecotourism projects will be able to tap this potential.