This chapter analyzes the origins and impact of union democratization movements in the Mexican automobile industry. The first part of the chapter explores the political context that led to liberalization of government labor policy. The second part gives a brief history of several Mexican automobile unions, placing special emphasis on the internal politics of each union. Here I focus on changes that occurred between unions and the CTM during the period of union democratization. The conclusion of the chapter provides a comparative, over time analysis of governing practices in nine unions.