This literature review examines the historical and contemporary relationships between labor unions and worker cooperatives as distinct yet complementary vehicles for worker empowerment. The first section introduces and compares the respective traditions, strengths, and challenges of unions and worker cooperatives. The second section overviews the motivations, history, and strategies for collaboration between unions and worker cooperatives. Such strategies, demonstrated through case studies, include incubation, resource sharing, and knowledge exchange. Finally, this literature review investigates the theory and application of the United Steelworkers-Mondragon union cooperative model, highlighting both its benefits and challenges. This analysis provides insights into the potential for a more integrated and powerful labor movement that combines the strengths of both unionization and worker ownership.