Many individuals with expertise on peacemaking will gather at the Vatican from April 11-13 to reflect on Catholic social teaching related to war and ongoing violence. It is fitting that the conference opens on the anniversary of Pope John XXIII’s Pacem in Terris (1963). We are invited to be in solidarity with the participants and to pray for the Holy Spirit’s guidance. NCR offers information about the importance of the Conference and Pax Christi International offers a prayer resource. For centuries the Church has held to the Just War Theory, and now may be critically reassessing that stance.