Szybowcowy Zakład Doświadczalny (SZD), Glider Experimental Works was a glider design and research centre of the Polish aerospace industry after World War II, located in Bielsko-Biała. Through its history it underwent many organizational and name changes, among others in 1946-1948 it was Instytut Szybownictwa. After 1969 it existed under other names, but an abbreviation SZD continued to be used on designs. The SZD gliders themselves were produced in the production centre in Bielsko-Biała, organized around the SZD (from 1990s named PZL-Bielsko), and by several other works of the state aerospace industry and didn't bear specific manufacturer's names.
Just after World War II, which destroyed most of Polish pre-war gliders and - more importantly - their production blueprints, the Main Scouts' Gliding Centre (Centralny Harcerski Ośrodek Szybowcowy) was created in Bielsko-Biała in May 1945, by the Ministry of Communications. In autumn 1945 it was re-organized into the Gliding Organizational Centre (Ośrodek Organizacji Szybownictwa), and in January 1946, into the Gliding Institute (Instytut Szybownictwa, IS). It inherited tasks and traditions of the pre-war Gliding and Motor gliding Institute in Lwów. It consisted of Training Division, Technical Division and Experimental Workshops. As more organizations took on a gliding training, the main task of the Institute became design work and technical research. At that period, several gliders were designed, under IS designation.
As a sign of new tasks, in 1948 the Gliding Institute was renamed to the Glider Experimental Works (Szybowcowy Zakład Doświadczalny), headed first by Władysław Nowakowski. It became the main Polish centre of designing gliders, which were next produced by the SZD workshops or, in conditions of a centrally planned state economy, by other state-owned workshops and factories.
In early 1950s, the SZD was incorporated into a Sports Aviation Equipment Works Management (Zarząd Zakładów Sprzętu Lotnictwa Sportowego), as a design centre. The management covered also glider production works (ZSLS) in Jeżów (Grunau),Gdańsk-Wrzeszcz (until 1954), Poznań, Krosno and Wrocław (from 1956). In 1957 this management was subordinated to the Central Management of Communications Equipment Industry (later PZL Aerospace Industry Union).