Central to the United Nations’ post-2015 development agenda grounded in the Sustainable Development Goals is the notion of ‘decoupling’: the need to divorce economic growth from its ecological impact. For proponents, decoupling entails increasing the efficiency with which value is derived from natural resources in order to reconcile indefinite economic growth with environmental sustainability. However, even advocates admit that the idea of decoupling remains poorly conceptualized and subject to scant empirical investigation. This persistent commitment to a highly questionable idea suggests the possibility of a deeper psychological dynamic at work here. Drawing on Lacanian psychoanalytic theory, in this article we therefore analyze decoupling as a ‘fantasy’ that functions to obfuscate fundamental tensions among the goals of poverty alleviation, environmental sustainability, and profitable enterprise that it is intended to reconcile. In this way, decoupling serves to sustain faith in the possibility of attaining sustainable development within the context of a neoliberal capitalist economy that necessitates continual growth to confront inherent contradictions.