EXITT is a computer model that simulates the decisions and actions of occupants in a residence. This model can be used to determine the locations of the occupants during the progress of a given fire. The rules for the action choices of the occupants are based largely on studies of residential fires and to a lesser extent on relevant controlled experiments. These rules involve consideration of the smoke conditions, and the characteristics, capabilities and locations of the occupants. EXITT can be run on a personal computer and does not require user training - the user controls the model by answering simple questions that appear on the screen. It can be run with preselected scenarios and, also, with buildings, fires and occupants selected by the user.