The US LTER network has grown rapidly over the past 20 years, both in size and in the scope of its activities. This growth is generally welcomed and is viewed overall as a mark of the success of the network and its individual sites and investigators. From an initial group of 6 LTER sites and a few dozen investigators in 1980, the network has grown to 24 sites in 2001, involving the work of hundreds of scientists, students, and teachers from scores of institutions at all levels of research and education. The LTER enterprise is unique in the ecological community.