The early twentieth century was a period of rapid growth and social change in America. The daily lives of women in particular were transformed due to increased rights and accessibility to public spaces. Thus, a new type of room developed for the exclusive use of women. Called a ladies’ rest room, these public rooms were originally established in the late nineteenth century to give women a designated space to rest, care for their children, and socialize with other women, in a town or city setting of mostly male-dominated, public spaces. Although the operation of ladies’ rest rooms continued throughout the 1920s and early 1930s, by the late 1930s the use of these rooms declined and fewer examples are found. As the need for segregated spaces for women declined, the rooms once used as ladies’ rest rooms typically assumed other functions. Consequently, little is known about the existence of these rooms today. The study of ladies’ rest rooms can inform our understanding of the changing dynamics of gender roles during the early twentieth century. Therefore, this paper explores the ladies’ rest room using a systematic approach to understand their development and decline at a time of great social change. To understand the evolution of these spaces, I created a typology based on the room’s location, function, and time period of use. This typology draws on a preliminary survey of ladies’ rest rooms using evidence from various historical newspapers, publications, and other primary sources. The typology forms the basis for an analysis of the ways in which the evolution of the ladies’ rest rooms parallels social changes in American society during the early twentieth century. The paper concludes with an assessment of how ladies’ rest rooms demonstrate that preservationists should look more closely at the evolution of interior spaces.