Why do claims of cultural belonging promote institutional transformation by expanding community boundaries in some instances and constricting them in others? To address this question, I introduce an elite-capital conflict approach, which synthesizes Bourdieu’s concept of capital with elite-conflict theories. I argue that this approach is valuable for understanding key aspects of mass mobilization such as the conditions under which marginalized elites will attempt to mobilize non-elites through appeals of cultural similarity; the factors which shape the cultural boundaries that these appeals propose; and when non-elites are likely to answer an elites’ call to mobilize. Drawing on historical analysis of 19th-century nationalism in Congress Poland, I show that the degree of capital concentration in the hands of Polish elites and conversion rates between different types of capital determined whether, and how, Polish elites utilized appeals to shared beliefs and practices as grounds for mobilization of non-elites. Whether appeals to shared cultural practices became a successful basis of widespread mobilization, however, depended on the benefits for non-elites of the reconceptualization or re-valuation of Polish culture and its boundaries that Polish elites were proposing.