Data came from observations and ratings of citizens who volunteered for training as mediators for a community dispute resolution center. The subjects were observed in a 30-minute simulation of a labor-management dispute prior to their training. After completing their training, they were observed in one role play and in their first and third actual mediations. Prior to the first role play, trainers completed the Thomas-Kilman Conflict Inventory, which indicates an individual's main conflict management style as either competitive, collaborative, accommodating, avoiding, or compromising. Demographic information was also collected. The analysis suggested the usefulness of the inventory and demographic information for predicting mediator effectiveness. These data sources may also provide the basis for specialized or remedial training for individuals who may be predicted to be deficient in some aspect of mediator skills or behavior.