This paper provides a critical assessment of the conceptions of social networks in systems theory. There are two main solutions to the problem: treating networks as systems, or denying them that status. The last group conceives networks as structural couplings (Kämper and Schmidt) or as forms (Fuhse). Among the first group, Luhmann has used the concept to describe the particularities of the societal structure of underdeveloped regions, but he did not delve into a theoretical characterization of the concept. Teubner’s version also remained associated with a particular episode, providing no general network theory. Bommes and Tacke establish reciprocity as the central mechanism, which relates different addresses (persons or organizations) through a non-specific future promise of a service in return for a favor. The analysis shows that this account provides the most complete version of the concept, remaining fully compatible with systems theory.