Describes an early detection and warning system (EDWS) for fires in buildings and examines the technological and economic feasibility of its widespread installation in New York City. Since the early minutes of a fire may be the most crucial, particularly in terms of loss of life, the fire department needs to know as soon as possible both that its services are needed and where it should respond. Yet this does not happen until someone notices the fire and reports it. This report suggests a potential solution involving the automatic detection of incipient fires and the automatic transmission of alarms and alarm information directly to the fire department. It appears that a large scale EDWS using ionization detectors is technologically feasible and could be economically attractive. A definite statement of its economic feasibility would require further study, which should center on two areas: fire losses and EDWS operational characteristics.