Abstract: From the late nineteenth century until the 1930s, American employers hired private detectives to go undercover in their factories to get information on theft and union organizing, and later, on the efficiency of their workers. During World War One those “labor spies” developed another practice neglected by historians. Rather than acting as an employer’s eyes and ears, the new “propaganda work” involved being the employer’s voice. Operatives repeated arguments drawn from management literature to change how workers thought about their relationship with their employer, to address the causes of their discontent rather than its symptoms, and developed friendships with employees sufficiently intimate that they would listen to arguments made to them. Propaganda work was thus more tied to ideas about management and to economic circumstances, and more invasive of everyday life than the other practices of labor spies. This paper explores the development of this practice and how the circumstances of war and peace, and gender, effected its practice, by examining the work of two private detectives employed by the Fulton Bag and Cotton Mills.