This chapter reviews and reconciles two theories of voting. Rational man models treat voters as actors seeking to maximize their material self-interest. Because their policy knowledge is limited, they often rely on ideology, trusted figures, and information picked up in the course of everyday activities to reach a decision. By comparison, survey evidence has shown that many voters are social, i.e. routinely adopt the opinions of those around them. The chapter concludes by describing various theoretical frameworks which unify these models. The combined models typically predict new behaviors in which initially small majorities are typically amplified; established opinions resist change for long periods; and very dramatic, once-in-a-generation events can abruptly reshuffle voters beliefs.