Publisher Summary This chapter discusses the informational social comparison within a framework of opinion formation in which an opinion is conceived of as a preparatory set for action by the person (P) toward an object or issue(X). When P anticipates transaction with X, an opinion-forming imperative is induced in P to reduce ambivalence he or she may have toward X. There are two major strategies P may use to reduce ambivalence: reduce the opinion-forming imperative and/or generate supportive information. Subsumed under the latter strategy are several avenues classified into two broad categories of information generation, nonsocial and social. The nonsocial type is a subset of avenues that leads to the generation of information directly relating to specific features of X (e.g., pro and con arguments, positive and negative features), whereas the social category of avenues—e.g., social comparison—refers to indirect information relating to X generated via referral to others. The ubiquitous process of social projection, the tendency for P to assume that others (O's) share his or her opinion, is the basis for such informational social comparison. The three-tiered conception presented in the chapter, in which informational social comparison is based on a substructure of individual opinion dynamics overlaid on goal gradient processes, offers a deeper understanding of some of the older literature and enables to derive additional implications, some which have already been tested and others that are in the process of being tested.