Over the last century, much was researched in the field of Education, be its educational policies or more effective learning strategies. It is only recently that studies have begun to focus on the teachers. This article describes an investigation about how the knowledge of teachers working in the field of Environmental Education is formed, transformed, and accessed. For this purpose, an ethnographical study of their narratives and practices was carried out. With the new century unfolding, it seems relevant to re-evaluate our learning purposes, as Education is considered to be an essential tool for the preservation of life on Earth. As teachers are privileged professionals in this process, elaboration of a new repertoire of professional teaching practices seems pressing. (Contains 2 notes.)