The Complex Systems Society promotes complex systems research, advises on complex systems education, and the relationships between complex systems and society by linking complex systems scientists of different countries. CSS also contains the Complex Systems Registry.
The Complex Systems Society at http://cssociety.org/ was first launched at a European level on 7th Dec 2004 during The European Conference on Complex Systems at Foundation ISI in Torino, Italy. It became an international society in 2006 during the ECCS06 Conference in Oxford.