Although House of Hospitality has received less scholarly attention than Dorothy Day’s other works, it remains an essential document for understanding Day’s spiritual evolution. This paper will examine the theological language and categories used by Day in House of Hospitality to interpret her work with the poor. As will be shown, in 1939 Day’s self-understanding of her work was still (compared to her later writings) relatively unsophisticated and unduly dependent upon the language of popular Catholic piety. This lack of any sustained and consistent theological vocabulary in House of Hospitality, I argue, reveals the importance of Day’s subsequent discovery of the Retreat Movement of Father Onesimus Lacouture, S.J. and its subsequent influence on her understanding of both her conversion and the meaning of the Catholic Worker movement. I conclude that, while it is clearly an imperfect and preliminary work, House of Hospitality offers a unique backdrop against which the distinctive spirituality of her mature works is revealed even more fully. As such, it remains an indispensable witness to her life and worthy of our continued attention.