The proliferation of financial practices and institutions throughout the mass of American society throughout the late nineteenth and early twentieth century produced a wide range of social effects. From changing discourses about racial progress and equality to aspirations for integrating rebellious workers into a system of financial-industrial capitalism, anxieties about financial panics to the possibilities of worker-owned cooperatives, popular engagement with the financial apparatus became the very stuff of American life. This dissertation looks at a wide range of primary sources—political pamphlets, bank statements, cooperative prospectuses, reform newspapers, trade journals, novels, and congressional testimony—to link changes in the form and nature of popular wealth to the development of mass politics. As the scattered but substantial wealth of the American working classes began to congeal in institutional forms, a wide variety of historical actors struggled over what to do with the people’s capital.