This chapter proposes an approach to modelling the functions of C2 performed over a network of geographically distributed entities. Any kind of command and control (C2) organisation, hierarchical, networked, or combinations thereof, can be represented with this approach. The chapter also discusses why a theory of C2 needs to be expressed in functions in order to support design and evaluation of C2 systems. The basic principle of how to model functions performed by network is borrowed from Cares’ network model of warfare, which is also used to model the context in which C2 is performed. The approach requires that C2 is conceived of as fulfilling a set of necessary and sufficient functions. Brehmer proposes such a theoretical model that is at a sufficiently high level of abstraction to illustrate the suggested approach. More detailed models will be required, however, for the approach to be of practical use.