The first Staff association of UNESCO (STA) was established in 1947. For the first 35 years of UNESCO existence, this organisation was the only association officially recognized by the Administration as representative of the UNESCO's staff.
In 1981 another staff association emerged: the ISAU (International Staff Association of UNESCO). Both associations, the STA and ISAU represent all different groups of UNESCO Staff members and have the same functions and activities.
In 1995/96 the STA changed its name from UNESCO Staff Association into UNESCO Staff Union (STU) in order to respond to a demand of FICSA (Federation of International Civil Servants' Associations). Despite the change of name, the organisation and activities of the associations stayed the same.

Over the years, there have been several attempts to divide the existing two staff associations in order to create associations who would be responsible for only the General or Professional Staff. But none of these attempts have been successful or would have been recognized as representative for UNESCO Staff.

In 1991, a new kind of association emerged: the AFUS (Association of former UNESCO Staff) who deals with all kind of questions concerning the former Staff members of UNESCO.