This chapter demonstrates the centrality of social psychological theories and research to scholarship on politics and the state. Showing how research programs on identity, emotion, legitimacy, social exchange, and trust illuminate core issues of politics and power at the micro, meso, and macro levels, the chapter also emphasizes that researching politics with a social psychological lens helps build social psychological knowledge. Among micro-level topics discussed that have important implications for politics and state power at the meso and macro levels are political identity as conceived in identity theory, individual variation in ideological and affective polarization, individuals’ perceptions of political incivility, individual variation in political and social trust, and individual variability in perceptions of political and legal legitimacy. Yet other micro-level topics discussed that have meso and macro-level implications are the emotional bases of politics and social movements, and individuals’ recruitment to, and participation in, social movements. Among topics discussed at the meso level but also with implications for the macro level are political identity as a social identity, the legitimacy of social movements and social movement dynamics, and trust networks. Among topics discussed at the macro level are the political cohesion of business elites, state legitimacy, the political and legal stability of states, and political and legal change, including regime change.