Internationalisation is a hallmark of modern science. Though, in the historiography of theology, processes of transnational and global communication are a long-neglected topic. This volume unearths the enormous wealth of international and inter-denominational transfers between different theological cultures from ca. 1800 into the 1970s. In 18 case studies and one comprehensive introduction, leading experts from different denominational backgrounds analyse a complex history of mutual entanglement as well as controversy over intellectual and dogmatic boundaries within a global horizon. Attention is given to well-established international centres of academic theology like Rome, Tübingen, or Princeton as well as the breeding grounds of theological innovation, like ecumenical circles or institutions of missionary theology. Topics range from international conferences, academics' networks and the influence of religious orders on the transfer of theological thought, translations and international publishing strategies to the importance of theologians' emigration or exile as a stimulus for cross-border awareness and discussion. By reconstructing the biographical, institutional, religious and intellectual contexts of worldwide theological communication, a new and fascinating chapter is added to the history of modern theology.