This paper draws on the theoretical reflections of two well-known ethnologists on indigenous Amazonian ontologies and moral philosophies, as well as my own field experience among an Amazonian native people, the Baniwa, in order to pose critical questions regarding the process of implementing ‘sustainable development’ projects. New ethnological perspectives challenge modernist thinking to de-colonize the ways in which scholars conceive of indigenous Amazonian cosmologies particularly with regard to such notions as ‘spirit’, ‘egalitarianism’, and ‘power’. The dramatic case of a Baniwa leader illustrates the heuristic value of taking Baniwa moral philosophy and cosmological framework seriously prior to and during the implementation of a recent artwork development project. The reflections of a Baniwa intellectual reinforce the pressing need to rethink current developmentalist thinking that ignores these frameworks.