The International Long-term Ecological Research network (ILTER) was founded in 1993 during the United States’ Long-term Ecological Research (US-LTER) All Scientists Meeting at Estes Park, Colorado, USA. ILTER was formed to meet the growing need for global communication and collaboration among long-term ecological researchers. Thirty-nine scientists and administrators representing sixteen countries participated in this meeting.

ILTER grew out of a realization within the US-LTER that it was not broad enough to effectively describe long-term ecological phenomena in the context of global change. If the scientific community was going to be able to provide the information necessary to implement Agenda 21 it would need long-term data from a diversity of ecosystems across the globe. With this realization emerged an interest on the part of the US National Science Foundation (NSF) to help catalyze the development of long-term ecological research programs in other parts of the world. NSF funded US scientists to reach out to colleagues throughout the world to help them establish long-term ecological research networks. 

Since ILTER’s establishment in 1993, global long-term ecological research programs have expanded rapidly, reflecting the increased appreciation of the importance of long-term research in assessing and resolving complex environmental issues. As of March 2016, 43 countries have established formal LTER programs and joined the ILTER network. Several more are actively pursuing the establishment of national-level networks and many others have expressed interest. ILTER began grouping its national-level networks into regions in 1996, and now has five regional networks – East Asia/Pacific, Europe, Africa, North America, and Central/South America.