Achieving a sustainable energy system obviously is an important goal of all societies. However, achieving that goal is complicated by multiple players with divergent interests promoting their views in the context of numerous complex technological considerations. The research described in this paper provides insights gained from the development of a multiple criteria decision-aiding process to aid such decisions and from an evaluation of convergence in decision maker opinion achievable using the process. The ability of an interactive multicriteria decision-aiding tool to facilitate convergence of decision maker opinions was tested in three phases: (1) development of an objectives hierarchy, (2) definitional clarifications, and (3) elicitation and refinement of criteria weights using shared judgment rationales. Each of these phases was conducted via repeated interactions among a disparate group of experts. Contrary to initial expectations of greatest convergence during the second and third phases of definitional clarification and weight elicitation and refinement, it was found that most convergence occurred during the initial objectives hierarchy development phase. This result demonstrates the value of structured thinking and interaction among decision makers. The structure of the exploratory model developed in this research and the insights gained may be useful for a wide range of real-world issues. (c) 2005 Elsevier Ltd. All rights reserved.