Designed in the late 1930s as a stable mate of the famous Beech Staggerwing, the Model 18 was intended to combine comfort and safety with the ability to operate from small airfields at low cost. The prototype first flew in January 1937. Initially the Model 18 was considered under-powered when compared to the similar Lockheed Electra Junior. The Model S18D introduced more powerful Jacobs L-6 engines which improved the performance. The S18D was capable of being flown from skis or floats as well as from conventional landing gear. During World War II, the Allies used large numbers of modified Model 18s as trainers.