Throughout the 1970ies a number of European aircraft manufacturers looked at a new regional turboprop of around 40 seats. Aérospatiale unveiled it's AS35 proposal at the 1979 Paris Show. It was Aérospatiale which took the lead in the formation of the consortium that would eventually end up producing the ATR, which is perhaps why the ATR 42 owed a great deal to the AS35.

After numerous discussions were held between Aérospatiale and the likes of Embraer, Lockheed and de Havilland; Aérospatiale entered into more fruitful talks with Aeritalia, the latter having a similar design in it's AIT-230-204. Both companies realized that the 'low thirties' seating end of the market had been fulfilled by the likes of the DHC 8, Saab 340 and EMB 120 Brasillia, the two companies realized they would need to come up with an aircraft in the 50-70 seater region.

An agreement was signed in July 1980 for a six month joint evaluation period, project definition was rapid and an outline for the 42 seat ATR 42 was dislayed at the 1981 Paris Show.

The ATR company, in which each partner had a 50% production share, estimated sales of 500 aircraft by the end of the century, which was not a bad guess considering a little over 600 ATR's are flying today. By October 1981 ATR had options payments for 56 aircraft from 14 airlines, more than enough to formally launch the programme, which took place on October 29.

Design crystallized on the Pratt & Whitney PW120 powered ATR 42-100 and the slightly heavier ATR 42-200, the latter having a 46 seat capacity. Prototype F-WEGA first flew on August 16, 1984, and was soon joined by second prototype F-WEGB. It was soon discovered that the aircraft would exceed the performance predictions. The ATR 42-100 was abandoned and the work continued on the ATR 42-200, although further weight changes, primarily in terms of payload resulted in the ATR 42-300. FAA certification was acheived on October 25, 1985. The first ATR 42 entered service with French Air Littoral in late 1985, the first US operator Command Air, took delivery of it's first example in January 1986. Within six months of entering service ATR were operational on all five continents.

Design studies into a larger variant, crystallized around the 64-74 seater ATR 72. It featured a 4.84m (14ft 9in) lengthening to the fuselage, and had wingspan increased by 2.48m (8ft 2in). Numerous other small changes were also performed to systems, such as the engine mounts for the uprated PW 120engines. Maiden flight of the ATR 72 was performed on October 27 1988. First order for the ATR 72 came from Finnair subsidary Kar Air. And first delivery to that airline was on October 30, 1989. An enhanced ATR 72 referred to as the ATR 72-210 was later announced, this version had more powerful PW127 engines, for better hot and high performance.

With this new engine the ATR 42-500 was launched as the new generation ATR, it included new features like: A new style interior, lower cabin noise and vibration, 300kt cruise speed, greater payload range capability, better airfield performance, lower external noise, higher specification standard, maintainability enhancements. Mexican carrier Aeromar Airlines, became the lauch customer.