A newly forming model treatment program for seriously mentally ill adults was dramatically affected by a natural disaster in September 1989. Hurricane Hugo rendered the offices of the Assertive Community Treatment Program uninhabitable, its vehicles marginally driveable, and its resources virtually nonexistent. In the three months following the storm, however, not a single psychiatric rehospitalization took place. Although the authors cannot claim that the program model was solely responsible for this outcome, this paper illustrates the service system elements that contributed to the program's effectiveness in the wake of one of the nation's most severe natural disasters.