After studying at several gymnasia, Siegmund-Schultze studied philosophy and theology in Breslau and Magdeburg. In 1908 he became the secretary of the Church Committee for friendly relations between Great Britain and Germany and later secretary to the World Christian Student League for social work and foreign mission. In 1911 he and his wife founded the "Soziale Arbeitergemeinschaft Berlin-Ost" - its offices were shut down after the Nazi seizure of power. At the World Churches Conference in Konstanz from 1 to 3 August 1914, just before the outbreak of war, he was secretary and co-founder of the "Weltbundes für Freundschaftsarbeit der Kirchen" and formed a pact with his fellow-delegate English QuakerHenry Hodgkin that led to the formation of the Fellowship of Reconciliation and the International Fellowship of Reconciliation. During the First World War he organised Gefangenenseelsorge for British and German prisoners of war. Through his contacts with the Quakers and with the "Versöhnungsbund", he and Elisabeth Rotten organised Quaker meals for schoolchildren in Berlin. In 1915 he met the Dutch pacifist Kees Boeke in Berlin. October 1918 the founder of ecumenism, archbishopNathan Söderblom, invited him to give a guest lecture on "The social renewal of Christianity and the unity of the Church"at Uppsala University. In 1925 Siegmund-Schultze received the professorship in "Jugendkunde und Jugendwohlfahrt" at the University of Berlin. In spring 1933 he joined the foundation of an international aid-committee for German-Jewish refugees. The Nazis arrested him and expelled from Germany under Gestapobegleitung 1933 with his wife and four children. They went to live in Switzerland and he was active there in student chaplaincy and as a guest lecturer until 1946. In 1947 he was made professor of "Sozialpädagogik und Sozialethik" at the Westfälischen Wilhelms-Universitat at Münster. In 1948 he founded the "Jugend-Wohlfahrtsschule Dortmund", and was its head until 1954. In 1959 he founded the Ecumenical Archive in Soest, which later received the central archive of the EKD in Berlin. Siegmund-Schultze was friends with Albert Schweitzer and published the Ökumenischen Jahrbuchs.
