The story
Established in 1986 as German Social Science Infrastructure Services (Gesellschaft Sozialwissenschaftlicher Infrastruktureinrichtungen), GESIS originally consisted of the three independent institutes:
Social Science Information Centre (InformationsZentrum Sozialwissenschaften, IZ) in Bonn,
Central Archive for Empirical Social Research (Zentralarchiv für Empirische Sozialforschung, ZA) in Cologne, and
Centre for Survey Research and Methodology (Zentrum für Umfragen, Methoden und Analysen, ZUMA) in Mannheim.
In 2007, the three GESIS institutes merged into one. In November 2008, GESIS added "Leibniz Institute for the Social Sciences" to its name in order to emphasize its membership in the Leibniz Association.
In November 2011, GESIS Bonn and Cologne were merged into one location in Cologne.
From Wikipedia’s article on GESIS – Leibniz Institute for the Social Sciences, shared under CC BY-SA 4.0.4