My project uses multi-sited interview and archival research to study the relationship between global union federations and transnational working-class formation through an examination of federations' efforts to organize complementary solidarity education and action among dockworkers' unions in the United States, the Southern Cone and Europe. While a large body of literature has examined class formation at the national level, very little research has been done on transnational working-class formation. This lack of research is surprising given the growing interest among social scientists, movement practitioners and policy makers in understanding the effects of economic globalization on workers. While the globalization of capital has arguably led to many adverse consequences for organized labor, it may also present an opportunity for new forms of transnational organization that could facilitate improved outcomes for workers. I examine these possibilities through a comparative case study of two international federations of dockworkers' unions, the International Transportation Workers Federation and the International Dockworkers' Council. Dockworkers play a crucial role in the flow of commodities in the global economy, and the nature of their work requires a significant degree of international coordination, making them excellent candidates for a study of labor federations and transnational class organization. The comparative dimension of my study allows me to examine the effects of organizational form, federation politics, alliance structures and national contexts on transnational class formation among dockworkers through nested comparisons in three global regions. My project thus sits at the intersection of political sociology, labor sociology, comparative historical sociology, the sociology of globalization and labor history, and promises to yield important insights into processes of transnational class formation and labor standards in the global economy.