This article emphasizes the crucial links between gender, working-class formation, and postrevolutionary statebuilding in Mexico. During the 1940s, textile unions in Puebla defined and implemented gendered conceptions of working-class identities and beliefs about men and women's proper roles within the sexual division of labor. Union leaders employed concepts of working-class honor to foster bonds of masculinity that in turn became the foundation for union authority and revolutionary working-class identities. These bonds subsequently underpinned union efforts to establish regional influence amid the union strife and political conflicts that persistently plagued postrevolutionary Puebla. To justify women's exclusion from factory and union life, unions concurrently promoted an ideal of working-class femininity, identified with home-based domesticity and scientific definitions of modern motherhood. This article ultimately suggests the important connections between industrial masculinization, modernization, and statebuilding in twentieth-century Mexico.