This article examines struggles over smoking privileges on industrial shop floors during World War II. I argue that workers' wartime demands for an end to employer smoking prohibitions contributed significantly to several noteworthy strikes in automobile factories and defense plants. Workers' pursuit of their smoking habit led them to push back some of the constraints of assembly line work discipline and employer rule making that defined mass-production industry during the early to mid-twentieth century, ultimately creating spaces of autonomy and rest within the rigidity and monotony of their work. As workers smoked on the job and struck to defend their habit, union officials found themselves working on behalf of their members to prevent employers from laying off or firing workers for violating companies' smoking bans. Struggles over smoking at work would play an important (but overlooked) role in the growth of organized labor during the 1940s.