The basic nature of science, as well as life, is that there will always be uncertainty. We define uncertainty as a situation in which a decision-maker (scientist, manager, or policy maker) has neither certainty nor reasonable probability estimates available to make a decision. In ecological science we have the added burden of dealing with the inherent complexity of ecological systems. In addition, ecological systems are greatly affected by chance events, further muddying our ability to make predictions based on empirical data. Therefore, one of the most difficult aspects of translating ecological and environmental science into policy is the uncertainty that bounds the interpretation of scientific results. That uncertainty in turn sometimes limits the willingness of policy-makers to incorporate scientific information in decision-making, and can even limit the willingness of scientists to offer input. Given the difficulties involved with translating scientific uncertainty to policy-makers and the general public, the Public Affairs Committee proposes to conduct a half-day symposium with the following objectives: (1) explore the role scientific uncertainty plays or does not play in the development of environmental policy; (2) present ways in which ecologists can communicate scientific uncertainty; and (3) use case studies where ecological knowledge and the uncertainty related to that knowledge were used to successfully implement sustainable environmental policy or management systems. The structure of the symposium will be as follows: each talk will be 20 minutes in length with the exception of the introduction (10 minutes) and the Panel Discussion (40 minutes). The speakers invited to the symposium represent a diverse group of experts including scientists representing disciplines from ecology, hydrology, political science, as well as scientific communication. The multidisciplinary nature of the invited speakers will result in a variety of topical themes ranging from the communication of uncertainties related to forecasting global climate change to uncertainties in water supplies and disease transmission. Each speaker will be asked to specifically address the scientific uncertainty related to her/his research or subject area, the role it plays in the making of public policy with specific references to sustainable outcomes, and how s/he translates or communicates the uncertainty of a focal system or results to the public.