Mediation, which involves a third party who attempts to facilitate voluntary agreements between two or more disputing parties, is an important component of industrial, international, and organizational disputes. Past research has provided little systematic information about mediation, and virtually no theory. This research is designed to develop a better understanding of the antecedents and consequences of mediation, and to evaluate its effectiveness. The investigators have developed a theory of mediation that proposes that mediator incentives and mediator beliefs about the likelihood of agreement interact to predict mediator strategy and negotiator responses to mediation. The results of preliminary experiments support the theory, and thirteen laboratory experiments have been designed to test additional hypothses derived from the theory and related propositions. The hypotheses concern the impact of mediator expertise and accountability on mediator perceptions and mediator choice of strategy; the behavior of biased mediators; the impact of expected mediator strategy, incentives, and two forms of mediator bias on negotiator receptivity to mediation; the effect of recommendations from expert and powerful mediators; and the impact of negotiator-mediator continuity on the effectiveness of mediation. In the experiments, subjects interact in simulated mediation and negotiation sessions. A record of their interaction is extensively coded. Outcome measures include negotiation and mediation tactics, negotiator offers, mediation recommendations, and the quality of agreements. The results of this research will be important for understanding how mediators function in different types of disputes where performance is dependent on optimal conditions, effective diagnosis of disputes, and the use of appropriate strategies. The results will suggest whether training and evaluation programs for mediators should stress contingencies in mediation, the idea being that certain mediator behaviors are effective in some circumstances and not in others. And the results will indicate possible important directions for future theory and research to evaluate and understand these contingencies.