This article is a historical study of the conflict about the environmental aspects of the Paraná Medio Hydroelectric Project in Argentina between 1995 and 1997. From an analysis of the discourses formulated by the coalitions which were for and against the venture and the field of possibility that gave rise to the conflict and its settlement, this study seeks to show how conflicts about the use of the territory are often framed in a dispute over truths. Using a qualitative approach, this article argues that it was not only a fight about extractive technologies which caused broader social struggles to be environmentalized, but the conflict also led to the emergence of new frameworks of thought about development and the environment, along with the associated historical conditions.