ESO, the European Organisation for Astronomical Research in the Southern Hemisphere, is an inter-governmental organisation with 14 Member States.

These member states are:

Austria

Belgium

Czech Republic

Denmark

Finland

France

Germany

Italy

Netherlands

Portugal

Spain

Sweden

Switzerland

United Kingdom

The Organisation is led by the Director General who is appointed by the ESO Council. The current Director-General is Prof. Tim de Zeeuw.

The main organisational and managerial units of ESO are the Directorates and Divisions. The Directorates are: Directorate of Programmes, Directorate of Operations, Directorate for Science, and Directorate of Engineering. The Divisions are: Telescope, Instrumentation, Technology, La Silla Paranal Observatory, ALMA Construction, Data Management and Operations, ST-ECF, Software Development, Administration, and Human Resources. Most of the divisions are located within a Directorate. Divisions are organised in Departments, some of which consist of two or more Groups.

For a detailed overview of ESO's organisational structure up to the level of Divisions, please consult the organigram of ESO (PDF) (as of 1 July 2010)