This paper aims to analyse the work that the Amazon Cooperation Treaty (TCA), later converted at the beginning of the 21st century into the Amazon Cooperation Treaty Organization (ACTO) with permanent secretariat in Brasilia, has conducted in favour of the debate on the sustainability of the Amazon. Although the work of this organization has usually been studied under a realist approach, focusing mainly on the action of its Member States, it is argued that the Complex Interdependence, a theory developed by Nye and Keohane, can expand the knowledge of the work of the Treaty in favour of the debate on the sustainability of the Amazon region