This report surveys and compares the approaches to prototyping adopted by four countries — Great Britain, France, Israel, and Sweden — during the development of similar new fighter/attack aircraft. It is based primarily on information gathered during interviews and briefings conducted in 1987 with senior government and industry officials of those countries. Basic fighter airframe development still carries sufficient risks and uncertainties to warrant the manufacture and flight testing of an austere airframe prototype before full-scale development (FSD) is undertaken. However, avionics development and integration are becoming areas of increasingly high technological complexity, uncertainty, and risk. Effective development and adequate testing and integration may be possible only with the help of sophisticated avionics ground labs and with fully missionized prototypes that are essentially pre-production FSD engineering test articles. The report concludes that a combination of both pre-FSD austere prototyping and missionized prototyping may be required to meet the challenges arising in the acquisition environment of the late 1980s.