In hostage negotiations, psychologists are not qualified to determine whether negotiations should be pursued or a tactical attack launched. Neither are they competent to make assessments about the dangerousness of the hostagetakers. Psychologists are generally not effective as negotiators because hostagetakers resent the implication that they are mentally ill. The psychologist can be most useful as a consultant on the negotiation team. As such, he/she should be trained with other team members and be exposed to information about hostage situations. The most important role of the psychologist as a member of the negotation team is to monitor the behavior of other team members, particularly the primary negotiator, and assess their reactions to the stressful situation. The psychologist can offer emotional support to the negotiator, make suggestions about how to deal with stress, and possibly alert the team leader to the undesirable impacts of stress on the negotiator's behavior. The psychologist can also be of value in providing post-event support to the negotiator and post-trauma counseling for the hostages. Other roles which the psychologist team member may fulfill are as (1) participant-observer in providing feedback on procedures, training adequacy, and the suitability of team members; (2) an interviewer of relatives, friends, and associates of both the hostagetakers and hostages to obtain information useful in negotiation strategy; (3) developers of decision aids to help police determine strategies; and (4) selectors and trainers and hostage negotiators as well as researchers focusing on the negotiation process. Nine references are provided.