ILTER (International Long-term Ecological Network) is the international umbrella organisation that governs LT(S)ER sites from around the world. It currently has 39 national member networks, which collectively operate more than 750 sites and are still growing. These ILTER member networks are made up of scientists engaged in long-term, site-based ecological (LTER) and socio-ecological research (LTSER).

Through the ILTER, it is possible to provide a globally distributed network and infrastructure of long-term research sites. It focuses on long-term, transdisciplinary research in biodiversity studies, socio-ecological research, and vulnerable zone management.