This chapter introduces three components of attitudes: cognition, evaluation, and behavioral predisposition. An attitude is based on a set of cognitions or knowledge structures associated with the attitude object. An attitude also involves a predisposition to respond or a behavioral tendency toward the object. Sentiment relations are evaluative and based on positive or negative evaluation. Attitudes are useful; they may serve heuristic and knowledge functions, and they define and maintain self. Affective-cognitive consistency not only predicts behavior but also increases the resistance of attitudes to change. Greater consistency between the cognitive and affective components is associated with greater attitude stability and resistance to persuasion. Elias Dinas argues that postdecisional dissonance and the cognitive efforts individuals use to reduce that dissonance partially explains the effects of voting on subsequent party identification. The chapter considers the accessibility and activation of the attitude, the characteristics of the attitude, the correspondence between attitude and behavior, and situational constraints on behavior.