In recent decades, sociologists have generally avoided explicitly discussing the role of culture in processes of social inequality. We argue that the prevailing disciplinary theory of inequality, the framework laid out in Charles Tilly's Durable Inequality, necessarily relies on cognitive processes and cultural concepts. The four primary mechanisms driving inequality—exploitation, opportunity hoarding, emulation, and adaptation—involve justification, categorization, coordination, and (e)valuation. We survey research on social inequality that illustrates each of these four processes. Our review reveals important empirical patterns about how disparities between groups emerge and endure. We observe that while sociologists often conduct work that implicitly relies on cultural concepts, other social science disciplines are also doing vital work in this area because they engage directly with cultural concepts. We identify key areas where sociologists are well positioned to use cultural concepts to uncover important findings regarding inequality, as well as to propose interventions for mitigating or preventing inequality. Expected final online publication date for the Annual Review of Sociology, Volume 48 is July 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.