This dissertation presents an analysis of the material practice of hospitality in the Catholic Worker movement during the 1930s. Dorothy Day (1897-1980), a radical Catholic social activist, co-founded the Catholic Worker movement in 1932, and one of the movement’s goals was to provide hospitality to poor and unemployed people. Day’s understanding of hospitality, and consequently the practice of hospitality at Catholic Worker houses, was shaped by Day’s experiences as a radical during the 1910s and 1920s, her conversion to Roman Catholicism, and her notions of gender; each of these factors led Day to understand hospitality as consisting primarily in materially grounded practices that lead to the mutual identification of host and guest. Of particular importance to Catholic Worker hospitality were the materials of space and food, which, in addition to promoting the mutual identification of individual hosts and guests, also shaped the identity of the movement itself, the content of the Catholic Worker newspaper, and Day’s and her followers’ critique of bureaucratic, state-sponsored responses to social injustices. Furthermore, the practice of hospitality also provided members of the movement with an epistemological grounding for their critiques of social injustices by allowing them to encounter real presences—subjective, transcendent realities that members of the movement understood in theological language as encounters with Christ. As Day and her followers practiced hospitality, they had to contend with a number of forces of institutionalization that would place conditions on their hospitality and limit its transformative potential. Finally, this analysis contributes to ongoing discussions about the place of hospitality in the teaching of composition by noting that the teaching of writing is subject to similar forces of institutionalization; the ways that Day and her followers responded to such forces—especially through an emphasis on domesticity and religious faith—are important to consider because they suggest that writing teachers need to consider the spiritual roots of transformative hospitality.