Utterances like "Oh, we're just a group of friends" and "We don't have a leader, we're all equals" are often heard among members of a friendship network, but usually do not reflect reality. In general, friendship networks do show recognizable structures, but how these structures emerge is a question seldom addressed.

In this book, an answer to this question is given by the presentation of a dynamic individual oriented model that explains how a heterogeneous population of initially unrelated individuals (mutual strangers) can develop into a friendship network. The general elements of the model are developed on the basis of correspondences between the principles of object oriented modeling, automata networks, and methodological individualism in a graph theoretical representation.

Predictions of these models are compared with data that contain information about the development of friendship networks in classrooms.