Background: While economic insecurity adversely affects the well-being of sex workers, few studies examine economic interventions in this community. Extant interventions employ microfinance approaches and are limited in scope, scale, and sustainability. Critiques of microfinance initiatives highlight their inability to achieve economic and gender empowerment. Moreover, microfinance interventions among sex workers often fail to address structural causes of economic disempowerment, and do not increase economic agency. This dissertation examines an alternative economic intervention: the Usha Multi-purpose Cooperative Society (Usha), a bank operated by a sex worker's union in Kolkata, India. Examining the organizational structure, culture, and operations of the bank I explore the manner in which Usha addresses the critiques aimed at microfinance initiatives, and the manner in which it cultivates economic and political agency in the sex work community. Methods: Utilizing a mixed-methods case study design, I conducted 80 semi-structured interviews with Usha members (n=60) and staff (n=20), participant observation and document analysis. Additionally, I conducted quantitative analyses of the bank's administrative database (N=14,382). Modified grounded theory and regression models were utilized to analyze the qualitative and quantitative data, respectively. Results: Usha facilitates empowerment through two intersecting operational approaches: its interventions operate at the individual and community levels, while targeting logistical as well as political outcomes. Specifically, Usha offers individual logistical financial support to sex workers through savings and loans programs which reverse predatory practices used by other microfinance initiatives. Community-level logistical financial support is provided by investing in businesses and social programs which benefit the sex worker community. Usha fosters individual sex worker political agency by supporting professional identity, independent decision-making, and sex worker leadership. Community-level political agency is developed by undermining the influence of financially coercive community power-brokers such as madams and pimps, providing labor protections, and facilitating access to civil society institutions. Conclusion: Usha challenges neoliberal approaches that attribute poverty to individual shortcomings, and resists the neocolonial framing of sex workers as victims. These results advance our understanding of how microfinance interventions can support social movements and effect structural change.