This article considers how well the existing sociological literature on immigrant integration and assimilation responds to public fears over multiculturalism. The current backlash against multiculturalism rests on both its perceived negative effects for immigrants' socioeconomic integration and its failure to encourage civic and political cohesion. I offer a brief review of multiculturalism as political theory and public policy, demonstrating that multiculturalism addresses questions of citizenship and political incorporation, not socioeconomic integration. We have growing evidence that multiculturalism does not hurt immigrant citizenship or political integration, and might facilitate such processes. We know much less about the relationship between multiculturalism and socioeconomic outcomes. I discuss how sociologists have developed useful models of immigrants' socioeconomic assimilation but have paid scant attention to civic or political outcomes. They also have not adequately addressed the relationship between socioeconomic and political integration. We can, nonetheless, extrapolate from existing scholarship, and I outline two models of political integration that seem to emerge from the sociology of U.S. immigration: one of individual-level political assimilation, another of group-based political incorporation. I conclude by offering a number of hypotheses about the importance of “groupedness” for politics and the relationship between political action, multiculturalism, and socioeconomic integration.