COSMO stands for COnsortium for Small-scale MOdelling. The general goal of COSMO is to develop, improve and maintain a non-hydrostatic limited-area atmospheric model, originally the COSMO model and now the ICON (Limited-Area Mode). The model, which is used both for operational and for research applications by the members of the consortium and other licensed institutes. Licencing for external user is provided (See contacts).

COSMO's organization is directed by a steering committee (STC), composed of one representative from each national weather service and a scientific project manager (SPM) who acts as its executive manager.

The various tasks/projects are organized into groups, called work groups (WGs), priority projects (PPs) or priority tasks (PTs), according to their span, prospect or focus (WGs being the older and "wider" work units of the consortium). Their coordinators form committees that report through the scientific project manager. The scientific project manager and the work group coordinators form the scientific management committee (SMC).

The operations of these entities are formally defined in the "Terms of Reference" (ToR) documents. The figure below, shows how they relate to each other:

The Consortium was formed in October 1998, at the regular annual DWD (Germany) and MeteoSwiss (Switzerland) meeting. Next year, a Memorandum of Understanding (MoU) on the scientific collaboration in the field of non-hydrostatic modeling was signed by the Directors of DWD (Germany), MeteoSwiss (Switzerland), Met (Italy) and HNMS (Greece) in March/April 1999. The MoU has been replaced by an official COSMO Agreement, which was signed by the directors of these initial four national meteorological services on 3 October 2001.

In 2002, the National Weather Service of Poland (IMGW) joined the Consortium. Since then, the National Institute of Meteorology and Hydrology of Romania (NMA, 2006), the Federal Service of Hydrometeorology and Environmental Monitoring of the Russian Federation (RHM, 2009) and the Israel Meteorological Service (IMS, 2017) have joined.

The 1st COSMO Agreement was signed by the national services Directors on 21 September 2009. Lately, the COSMO partners decided to renew the Agreement and its current version was signed on 19 June 2014.