Matthew M. Mettler examines a 1939 strike of building service workers against Des Moines's largest and most popular department store, Younkers, and its allies in the city's nascent retailers' association that lasted for five weeks. Although the strike failed to achieve the workers' principal demand for a closed union shop, it marked the first time that the city's labor movement and civil rights movement began to reinforce one another. The Building Service Employees International Union local at the center of the strike was affiliated with the American Federation of Labor (AFL) and consisted of thirty-six janitors, porters, and workmen — twenty of whom were African American. This strike was the first majority African American picket line in the city's history, and the black community watched to see if the white labor movement would move beyond its history of racial exclusion. Leading the charge to break away from this history was the city's insurgent and militant Teamsters union, Local 90. The Des Moines Teamsters quickly transformed a dying local into the city's largest and most influential union in the city. Local 90 took over the city's venerated AFL Trades and Labor Assembly from craft unionists and first used it to revitalize Des Moines's working-class community and then extended it to include the city's African American workers. The Younkers strike illustrates an overlooked dynamism at the heart of AFL labor organization in the 1930s and shows how community-based unionism could provide the foundation for progress in race relations.