In her new book Blessed Are the Peacemakers: Pacifism, Just War, and Peacebuilding (Fortress Press, 2019), Monan Professor of Theology Lisa Sowle Cahill offers a historical understanding of pacifism and just war theory, while advocating a newer approach to conflict situations called peacebuilding. According to Cahill, peacebuilding seeks to transform conditions of violence and bring about a just and sustainable peace. It is particularly needed in the 21st century as evidence grows that other approaches have failed to achieve sustainable peace. She writes: “Peacebuilders agree on the preeminent importance of taking non-violent yet forceful measures to deter ongoing violence, undo social injustice, and bring opposed groups together around a negotiated vision of social coexistence and cooperation.”