Willpower has returned to contemporary psychology, drawing on ordinary speech, but the status of the will in psychology is not settled. Avoiding this antinomy of the will by proposing that willpower is an interactive kind (Hacking, 1999), this paper examines the significations of willpower as it developed in American culture and appeared in American newspapers from the 1850s to 1970. Willpower has diverse significations: self-control, resoluteness, and effort; testing of the limits of endurance; ability to influence and lead others; a visible sign of character; a measurable trait; a goal of education and training. Willpower was questioned, subordinated to other traits, and denied existence. Two conclusions arise: Qualitative research will enrich our understanding of willpower; and the history of willpower is essential to psychology’s understanding of it, showing willpower to be a category appropriate to societies where individual effort, despite circumstances and conventions, is a cultural good.