Technical Abstract: Environmental decision-making is complicated by the complexity of natural systems and the often competing needs of multiple stakeholders. Modelling tools are often used to assist at various stages of the environmental decision-making process. If such models are to provide effective decision support, the uncertainties associated with all aspects of the decision-making process need to be taken into account explicitly. However, as models become more complex in order to better represent integrated environmental, social and economic systems, achieving this goal becomes more difficult. Some of the important issues that need to be addressed in relation to the incorporation of uncertainty in environmental decision-making processes include (i) the development of appropriate risk-based performance criteria that are understood and accepted by a range of disciplines, (ii) the development of methods for quantifying the uncertainty associated with human input, (iii) the development of approaches and strategies for increasing the computational efficiency of integrated models, optimization methods and methods for estimating risk-based performance measures, and (iv) the development of an integrated framework that enables all sources of uncertainty to be incorporated in the environmental decision-making process.