In this chapter we have presented an approach to persuasion that focuses on the role of information in changing peoples' attitudes and on how people combine the information they receive into an overall impression. Common to all of the theories covered in this chapter is the view that an attitude is based on the information or beliefs that a person has about the attitude object. The probabilogical theories with which we began our discussion emphasized the interrelationships among a person's beliefs and how the change in one belief could lead to a change in others. These belief changes were shown to be governed by both logical and "wishful" thought processes. The theory of reasoned action viewed an attitude as a weighted sum of the information that a person had about an attitude object; and it further indicated that a person's behaviors were based on a consideration of one's own attitude and one's perceptions of the views of important other people. The theory of information integration was shown to allow description of a wide range of attitudinal phenomena with the fundamental principle that an attitude was best represented as a weighted average of information about an attitude object. The next chapter also emphasizes the role of information in persuasion but focuses on the information that people generate themselves rather than on information presented by external sources.