A co-founder of the Catholic Worker Movement, its newspaper, and hospitality houses, the writer Dorothy Day promoted public peace nationally and internationally as a journalist, an organizer of public protests, and a builder of associational communities. Drawing upon Hannah Arendt’s conceptions of the role of speech and action in creating the public realm, this paper focuses on several of Day’s most controversial public positions: her leadership of non-cooperation against Civil Defense drills intended to prepare New York City residents to survive a nuclear war; her urging of Catholics to find common cause with the Cuban revolutionary government; and her support for interracial farming communities in the Southern United States. As Arendt asserts about Rahel Varnhagen’s salon in Berlin, by being public meeting spaces hosted in private houses, Catholic Worker communities fostered egalitarian rather than “agonal” politics. Like Gandhi’s newspapers and ashrams as well as “Occupy” communities such as Zuccotti Park, Day’s newspaper was a center for incubating and implementing social reform. The Catholic Worker provided a place where writers could question the official rhetoric of such conflicts as World War II and the Cold War, put forward different interpretations of unfolding events, and chart possible alternatives to establishment agendas.