This work traces the development of social ethics in European Protestantism from Barth's early dialectical theology (circa 1920) through Bonhoeffer's Ethics written during World War II. In this development, two major approaches to social ethics emerge: a theological radicalism, championed by Barth, which emphasizes the difference between Christian action and ordinary moral reflection; and a theological realism, exemplified by Brunner and Bonhoeffer, which stresses the possibilities for Christian cooperation in making and sustaining the social order. A final chapter traces the continuing influence of these approaches in Christian ethics today.