In the caucus, the parties are physically separated. In addition, communication is intentionally restricted to increase the chance of a successful outcome to the negotiation. The caucus is usually shorter than a formal recess and aims to handle specific emotional, procedural, or substantive blocks to negotiation. External events that may produce the need for a caucus include changes in the legal, economic or political climate or actions taken by other parties that escalate the conflict or narrow the range of options for settlement. Internal events are of three types: (1) problems in interpersonal relationships between parties or within a team, (2) problems in the negotiation process, and (3) problems related to the substantive or content issues under discussion. Either the parties or the mediator can call for a caucus at any time. Issues the mediator should address include (1) educating the parties about the technique, (2) procedures for calling a caucus, (3) overcoming parties' resistance to separate meetings, (4) making the transition to the caucus, (5) determining the sequence of the meetings, and (6) determining the duration of the caucus. After handling the procedural, substantive, or psychological barriers to settlement in private, the mediator will usually encourage the parties to resume face-to-face dialog and will prepare them for reentry to the joint session. Mediators must also be aware of the ethical issues involved in caucusing. 1 figure and 17 references.