This study investigated the dynamics of communication between members of an emergency management team faced with controlling a hazardous chemical spill. The effects of two sets of factors on communication were investigated; task-specific factors pertaining to characteristics of the emergency management task that are constant across different emergency situations, and situation-specific factors pertaining to the unique characteristics of the current situation. The results showed that both these factors were important in determining the pattern of communication between key team members. Verbal exchanges were found both to be correlated with the occurrence of critical events and to follow a 30-minute temporal cycle. The implications of the results for theories of naturalistic decision making are discussed. Copyright (C) 2002 John Wiley Sons, Ltd.