Informal groups play a pivotal role in the socio-cognitive structuring and development of all scientific fields. While most social studies on such groups present a static view, taking a snapshot of them at a certain moment in time, this study sheds a dynamic perspective on invisible colleges and examines empirically how they evolve in the course of time. Drawing on the neo-Kuhnian sociology of science, it defines invisible colleges as communication networks and considers how their emergence and evolution is affected by the organizational features of fragmented adhocracies. The empirical aspect focuses on formal scholarly communication through publication in a sample of seven leading journals in the field of management and organization studies over three decades. The methodology is rooted in bibliometrics and combines co-citation analysis with network visualization. The resulting networks, which reflect the community structure of the field, map 40 different colleges. Seven patterns of how this nested structure evolves are derived: college appearance, transformation, drift, differentiation, fusion, implosion and revival. The paper closes with suggestions for further research on those patterns.