"This theory illustrates a way by which many complex phenomena about groups can be deduced from a few simple postulates about interpersonal relations. By the application of digraph theory we are able to treat in detail the patterns of relations whose importance has long been noted by the field theorists." Three major postulates are presented as well as a variety of theorems dealing with the effects of the power structure of the group, the effects of communication patterns, the effects of patterns of opinion, and leadership.