A realist discourse of risk currently dominates regulatory decision making for genetically modified organisms (GMOs).  This paper challenges the appropriateness of this for regulating the environmental impact of GMOs.  Discussing psychometric research, cultural theory and the development of typologies of uncertainty, I argue that there is an emerging theoretical shift away from a singular focus on quantifying risk, and towards the articulation of decision-making processes contrastingly constructed around the negotiation of uncertainty.  Key factors distinguishing these approaches include: the discourse of decision making, the role granted scientific knowledge, the avenues for public participation, the range of policy options considered, and the requirements for ongoing research and monitoring.  After establishing this theoretical framework, I analyse Australia's regulatory system for GMOs and conclude that although it is more accurately characterized as a risk-based approach to environmental decision making, there are ways in which a shift towards uncertainty can begin.