In the same week John F. Kennedy announced the Alliance for Progress, the Vatican mobilized Catholic sisters to wage a campaign against poverty in South America to undermine the appeal of communism. And not just that: Catholic sisters’ work—because of their access to the sphere of culture as teachers, nurses, midwives, catechists, and social workers—buttressed these imperial efforts. My dissertation analyzes how this development effort imposed imperial cultural systems through non-imperial means on the ground in clinics, social works centers, parishes, and schools in Chimbote, Peru. Yet, I also ask how Catholic sisters’ encounter with Peruvian people, politics, and theology challenged, undermined, and reoriented these efforts as well as how this encounter destabilized Catholic sisters’ religious, gender, and national identities. Scholarship on the politics of Western humanitarian aid continues to focus on the intellectual histories of U.S. diplomats and social scientists overlooking how development projects unfolded on the ground, how developers changed in the process, and how non-governmental actors shaped these initiatives. Conversely, I analyze how the failure of this twentieth-century crusade moved the largest religious institutional welfare system away from institutional charity and into grassroots advocacy efforts as well as sparked a Catholic feminist movement.