As cigarette smoking expanded dramatically during the early twentieth century, it brought more and more workers into conflict with the policies and demands of the manufacturers who employed them. As this paper shows, addiction to nicotine ignited daily struggles over workers’ shopfloor rights and the ability of employers to set rules, establish discipline, and monitor behavior. A specific set of records from the archives of the Hammermill Paper Company, a paper manufacturer once based in Erie, Pennsylvania, provide a unique opportunity to explore the impact of cigarette consumption on labor relations during the era of mass production, as two nosy factory spies probed and documented worker actions and attitudes in the summer of 1915. As a result of their intelligence gathering, the spies discovered a factory-wide work culture rooted in the addictive pleasure of cigarette smoke. This discovery worried them. Worker-smokers needed to dampen their hunger for nicotine with frequent, and often clandestine, breaks from work, typically in defiance of “no-smoking” rules, employer designations for the uses of factory space, and bosses’ demands for continuous production. Highlighting the intersections of the histories of labor, smoking, and addiction, this paper argues that cigarettes were a key battleground in workers’ and managers’ intensifying struggles over who really controlled the industrial shopfloor during the early 1900s.