“Top-down” and “bottom-up” perspectives on political polarization have unfolded on largely parallel tracks, without speaking too extensively to one another. In part, this is due to their roots in different disciplines: the top-down perspective has its origins in political science, whereas the bottom-up perspective comes out of personality and social psychology. Though the accounts of polarization offered by political scientists and psychologists are sometimes presented as antagonistic in their implications, they need not be. In this chapter, I review research aimed at integrating the top-down and bottom-up accounts of political differences in mass publics in an effort to develop a hybrid perspective on the bases of political polarization. Like the bottom-up psychological approach, the model I present argues that people are systematically attracted to different positions on the basis of individual differences in needs for security and certainty. However, like the top-down approach, it also contends that the tendency for those with different psychological dispositions to adopt polarized political preferences depends on exposure to elite political signals that provide information about the content and meaning of different ideological, partisan, and issue orientations—exposure which is likely to be more pronounced among politically engaged citizens.