The essay develops three central arguments. Firstly, while being one of the core concepts of sociology in the early 20th century, the group concept loses its central position between 1960 and 1970. As a conceptual tool for the understanding of configurations of social relationships, it is increasingly replaced by the network concept. Secondly, the group concept implies bounded social entities. The network concept, in contrast, stresses the unbounded interweaving of social ties and contexts. This allows for a better understanding of the complex social patterns of modernity. Thirdly, groups are special cases of "involuted" network structure. Here, a symbolically constructed social boundary becomes the central focus for transaction processes. This also makes for an increased alignment of social relationships within the group. These three arguments are grounded in a historical perspective on the conceptual careers of "groups" and "networks" in various sociological schools. The essay stresses the dynamics and inner logics of social relationships and resulting configurations (groups being one example) on the meso-level.