In this paper, we analyse the status and significance of adopting a Marxist ontological perspective in the field of Brazilian environmental education. We draw on the concept of labour developed by Marx, where labour is used as a category to articulate the relationships humans establish with nature and which, historically, have an impact on their living conditions. Given the ongoing process of destroying the material basis of life under a Capitalist means of production, we argue that environmental educators and researchers require refinements to the theoretical and methodological frameworks they use to understand contradictions between development and sustainability in Brazil. This includes meeting their responsibilities to help others and themselves overcome the current capitalist model governing the social and material production of life.