My book monograph dissertation studies "Opportunity Politics" in Rich Democracies. It offers a comparative political economy theory of education, housing, and financial systems as joint mediators of life chances and labor market opportunities in rich democracies, using both quantitative and qualitative methodology. The project explores how inter-dependencies in the function of these institutions in securing opportunity shape actors' strategies in political contestation between opportunity "insiders" and "outsiders" -- including through contesting the rules defining these institutional spheres -- focusing on the United States, Germany, and Japan as comparative cases across two historical periods: ~1945-1979 and ~1980-2010. While contributing to scholarship studying public opinion, economic behavior, and interest group politics in these policy areas separately, the dissertation's integrative and historical approach suggests that education, housing, and credit systems are best understood not as static and separable domains of pure distributive politics, but rather as joint functional mediators of inter-generational opportunity. Accordingly, conflict between coalitions of "outsider" families seeking greater access to opportunity with challengers to opportunity supply-side incumbents on the one hand and coalitions of "insider" families seeking to preserve privileged opportunity access with groups vested in status-quo institutions on the other help explain historical processes of both institutional change and persistence in these policy areas. The dissertation interprets this history across a diverse set of liberal democracies, ultimately offering a novel and thoroughly political theory explaining persistent gaps between the ideal-typical promise of opportunity-mediating institutions and their real world functional capacity to deliver equitable opportunity under conditions of structural economic transformation.