This chapter begins with a formal analysis of the conditions of consensus formation, based on our standard model. We include a formal analysis of the important special case of influence networks with binary susceptibilities in which each group member's susceptibility is strictly either 0, i.e., the person's initial position on an issue is not influenced by other group members, or 1, i.e., the person attaches no weight to his or her own initial position. Our theory and empirical evidence suggest that binary susceptibilities may be the rule, not the exception, in the formation of consensus through interpersonal influences. In the previous chapter, we noted that Milgram (1974) raised the fundamental empirical question of the nature of susceptibility in the context of his studies on obedience. Individuals appeared to be either in the cognitive state of an “agent” whose actions conformed to the preferences of an authority, or not in such a state. Our analysis suggests a broader hypothesis in which reaching consensus in a group, with members who are in initial disagreement on an issue, depends on the existence of members who accord no weight to their own initial positions on an issue. Such members shift their positions on an issue to a personal subjective norm, which is a weighted average of the time-t positions of other group members, at each time t during the influence process, and in so doing become the “agents” of that subjective norm even as the norm changes during the course of the influence process.