The US Long Term Ecological Research (LTER) program began in 1980 with the mission of addressing long-term ecological phenomena through research at individual sites, as well as comparative and synthetic activities among sites. We applied network science measures to assess how the LTER program has achieved its mission using intersite publications as the measure of collaboration. As it grew, the LTER program evolved from (a) a collection of independent sites (1981–1984) to (b) multiple ephemerally connected groupings with a gradual increase in collaboration (1985 to about 1998) to (c) a largely collaborative, densely connected network (from approximately 1999 on). Some sites demonstrated “preferential attachment”by contributing more to the evolution of network cohesion than others. Collaborative efforts of LTER scientists included cross-site measurements and comparions, information technology transfer, documentation of methodologies, and synthesis of ecological concepts. Network science provides insights that not only document the evolution of research networks but also may be prescriptive of mechanisms to enhance this evolution.