A disaster is the most acute example of an unusual situation and the disaster manager must operate in an environment in which pressures and events forge unusual combinations of people. The working environment is influenced by: 1) pressure; 2) inexperience of the workers; 3) perceptions; 4) working conditions; and 5) reactions of the worker to the disaster. Disaster workers are motivated by: 1) humanitarian concern; 2) happenstance; 3) excitement; 4) grief; 5) guilt; or/and 6) opportunism. Group dynamics include the formation and function of the “disaster community” and inter-organizational relationships. The disaster community evolves around the spontaneous appearance of natural leaders, but eventually, these leaders and the disaster community are replaced by more formal organizations that are part of the relief operations and that rarely include the disaster community. In the longer term, as reconstruction begins, the organizational structure becomes more professional. Each of these phases provokes different group dynamics that must be considered by the disaster managers. Such implications are outlined in the discussion.