Three South American countries, Argentina, Chile and Brazil, have been selected in order to study the impact of the document “The United Nations Decade of Education for Sustainable Development”. In these countries, whose people react energetically against any attempt to break the environmental balance, the synergic power of education is recognized. Therefore, it can be observed that the content sustainable development has been incorporated in the new educational schemes since 1990s in all their levels. The analysis in the formal, non formal and informal education of these countries shows us that they have the environmental issue well contemplated. But, it is necessary to emphasize the interrelations of three essential components: environment, society and economy in order to develop solidary values for improving a sustainable present and future existence. In relation to the “The United Nations Decade”, it is noticed that although different measures have been adopted, conjoint work by the region's countries from a Latin American perspective is required.