Object This study examines the effects of labor union membership and labor unions’ mobilization efforts on minority group members’ participation in voting. Methods It uses a hierarchical linear model with data from the Current Population Survey (2000, 2004, and 2008) and state‐level information. Results The analysis shows that the effect of union membership on voter turnout varies somewhat by racial and ethnic group. Also, it finds that labor unions’ mobilization efforts, measured by union density in states, significantly increase minority group members’ participation in voting more than it does that of whites. Finally, the effect of union density in states among Latinos changes significantly by political conditions. Conclusion Labor unions play an important role in assisting minority group members, who traditionally have been considered to lack resources as compared to whites, to participate in voting by engaging in voter mobilization at the state level as well as by increasing membership among minority members.