Mediation and mediation-arbitration (med-arb) are two forms of third-party conflict intervention that can affect integrative agreements in labor-management negotiation. In an attempt to evaluate the relative value of each of these two methods, 160 volunteers, almost all business students, were randomly placed into a mediation triad, a med-arb triad, or a no-third-party dyad. The negotiation task for each triad or dyad involved wage rate, cost of living increase, over-time rate, and health benefits. In the med-arb triads the negotiators were told that if they reached no agreement, the mediator would settle the dispute. The negotiators in the mediation triads, however, were told that the issue would remain unresolved if no agreement were reached. The highest joint outcomes were obtained in the med-arb triads; the lowest in the no-third-party dyads. These differences reflected the outcome of the person who did the best, not the outcome of the other negotiator. The outcome difference variable was greatest in the med-arb condition. This suggests that med-arb produced the most competitive atmosphere. Less trust, more insults, and greater interpersonal distance were reported in the med-arb triads. The results indicate that mediator power, as seen in a med-arb situation, produces a "chilling effect" and leads to more inequitable outcomes. The subject sample used in this study may explain the results differing from previous research. (TW)