This paper describes a prototype dual mode corrosion monitor capable of measuring both instantaneous corrosion rate and the cumulative corrosion loss in atmospheric environments. The system consists of two components: a small flat sensor to be located in the area to be monitored and a battery powered meter unit to query the sensor. The sensor element is made of steel which is far more sensitive to atmospheric corrosion than most other metals; thus the sensor will react before significant damage has been done to other materials. The sensor itself is actually two discrete sensors on the same substrate and photo-etched from the same foil. Corrosion rate is measured using two-electrode Linear Polarization Resistance (LPR) while cumulative loss is measured by the Electrical Resistance (ER) method. The meter has been designed for operation by personnel with minimal corrosion knowledge. Its primary purpose is to alert an operator of the existence of corrosive conditions, thereby allowing remedial action to be taken before extensive corrosion damage has occurred.