This literature review, commissioned by New Pluralists and authored by political scientists Justin Gest and Tyler Reny, synthesizes over 200 studies across psychology, political science, and sociology to examine what drives polarization tied to demographic change and identity politics in the U.S., and what might counter it. It concludes that relationship-based interventions built on everyday intergroup contact show the most consistent (if modest) promise for shifting attitudes toward pluralism, more so than one-off messaging interventions, while noting that most Americans are less deeply polarized than commonly assumed.