An Expert Support System (ESS) provides expert advice to complement the knowledge of the decision maker, and is intended to support , rather than replace, the decision maker. The ESS technology provides two fundamental functions: (1) the ability to perform analyses and draw conclusions by providing users with expert opinions, judgments, evaluations and advice; (2) the ability to explain its reasoning and conclusions. The usefulness of expert support technology has been evaluated in a number of empirical studies. However these studies either examined the organizational impact of the technology [e.g., 1] or the use of the technology by single individuals [e.g., 2]. No empirical study has yet examined the use of expert systems technology for supporting group decision. The aim of this research is to advance knowledge in this direction byinvestigating the usefulness of ESS for group decision support