PZL (Państwowe Zakłady Lotnicze - State Aviation Works) was the main Polish aerospace manufacturer of the interwar period, based in Warsaw, functioning in 1928-1939. The abbreviation was thereafter - from late 1950s - used as an aircraft brand and as a part of names of several Polish state-owned aerospace manufacturers referring to traditions of the PZL, belonging to the Zjednoczenie Przemysłu Lotniczego i Silnikowego PZL - PZL Aircraft and Engine Industry Union. After the fall of communism in Poland in 1989, these manufacturers became separate plants, still sharing the PZL name. In the case of PZL Mielec, the abbreviation was later developed as Polskie Zakłady Lotnicze - Polish Aviation Works.
The PZL - Państwowe Zakłady Lotnicze (State Aviation Works) was founded in Warsaw in 1928 as a state-owned company, and was based on the earlier CWL (Centralne Warsztaty Lotnicze) - Central Aviation Workshops. First to be produced was a licensed version of a French fighter, the Wibault 70, but from then on the company produced exclusively its own designs. In the next decade Zygmunt Puławski designed a series of high-wing, all-metal modern fighters: PZL P.1, P.6, P.7 and P.11. The last two types were used as basic fighters in the Polish Air Force from 1933 onwards. The last variant, PZL P.24, developed after Puławski's death in an air crash, was exported to four countries. PZL also mass-produced a light bomber, PZL.23 Karaś, and a modern medium bomber, PZL.37 Łoś, as well as building small numbers of sport aircraft (PZL.5, PZL.19, PZL.26), and liaison aircraft (PZL Ł.2); and developing prototypes of passenger aircraft. In the late 1930s the company also developed several prototypes of more modern fighters and bombers — and a passenger airliner, the PZL.44 Wicher. However, World War II prevented these aircraft from entering production. PZL was the largest Polish pre-war aircraft manufacturer. In 1934, the main factory in Warsaw was named PZL WP-1 (Wytwórnia Płatowców 1 - Airframe Works 1) in the Okęcie district of Warsaw. A new division PZL WP-2 was built in Mielec in 1938-1939, but production was only just starting there at the outbreak of World War II. An engine factory division, PZL WS-1 in Warsaw-Okęcie (Wytwórnia Silników - Engine Works 1), produced mostly licensed versions of British Bristol engines, such as the Bristol Pegasus and the Bristol Mercury. The WS-1 factory was formerly Polskie Zakłady Skody, the Polish division of Skoda Works, and was nationalized and renamed in 1936. In 1937-1939 a new engine division, PZL WS-2, was built in Rzeszów.