This article examines the American dress-reform movement, detailing the ways in which reformers conceptualized clothing as a social and bodily technology. In the mid-nineteenth century, women began making and wearing the “reform dress”—a costume consisting of pants and shortened, lightweight skirts—as an alternative to burdensome feminine fashions. When ridiculed in public for wearing overtly masculine garments, dress reformers insisted their clothing was healthful, functional, and natural. This article discusses women’s use of medical science and technical knowledge in their rejection of fashion, promotion of sexual equality, and efforts to change mainstream clothing practices. When approached from a technological perspective, the reform dress reveals broader tensions in an industrializing American society, such as changing gender relations and new understandings of the relationship between humans and technology.