"What does representation look like when focused on "othering" the opposing party? How do constituents react to such representation? Is policy responsiveness still the cornerstone of American representative democracy when negative partisan identities motivate political attitudes? How Politicians Polarize introduces a theory of representation to fit the contemporary context of polarization and negative partisanship. Using a series of survey experiments on elected officials, candidates, and individuals in the mass public, as well as large-scale text data of congressional newsletters and tweets, the book examines how and why politicians make partisan, out-group appeals and assess the consequences for the quality of political representation. Costa shows that even though Americans do not favor expressions of partisan animosity by politicians, and politicians do not think voters reward such expressions, the broader context of affective polarization nonetheless makes such behavior a powerful tool in representation. The findings challenge the popular notion that Americans are motivated more by their partisan identities than by policy congruence, but also illuminate how negative forms of representation are indeed still rewarded by the political ecosystem and the adverse effects this has on representative democracy"--