This article examines situational factors and mediation techniques associated with settlement and nonsettlement of collective bargaining disputes by means of mediation, using data from 260 mediation cases involving the British Advisory, Conciliation, and Arbitration Service. The results show that the nature of the issue in dispute, the source of request for assistance, and the threat or imposition of a strike during mediation all have a significant impact on the probability of settlement by mediation. The results provide support for many, but not all, of the mediation effects predicted as significant in the literature. The strongest determinants of mediated settlements were arranging preliminary meetings with the parties separately to explore the issues in dispute, assisting in the negotiators' relationships with their constituents, and threatening to quit if no progress was made in the negotiations. The use of directive mediation techniques was particularly effective when the dispute concerned nonsalary issues, or when a strike or lockout was imposed during the intervention.