Between 1968 and present, members of the Maryland Province of Sisters of Notre Dame de Namur (SNDN) participated in radical peace activity. These sisters cultivated a distinct religious identity and used the all-woman spaces of their order to define, support, and sustain their peace activism. The SNDN illuminate the vital role women religious played in shaping the form and longevity of the Catholic peace movement. Sisters were central to Catholic peace activity, drawing on their religious identity and linking their actions to work sanctioned by the Catholic Church. Between 1954 and 1970, the SNDN responded to changes in the Church and constructed a religious identity based in a Catholic feminist ideology. During the Vietnam War, sisters called upon this religious identity and their order’s support networks to motivate their activism. After the Vietnam War ended, the SNDN continued to cultivate their religious identity and maintained their peace activism within the Church.