This book explores how and why global Protestant movements have been foundational for studies of internationalism. During the early twentieth century, hopes for the peaceful coexistence of nations animated emerging international Protestant cooperation. Despite national hostilities including world war, commitment to global Christian fellowship became an urgent public agenda. In this volume, essays by European, Asian, and North American scholars locate the essence of the "young ecumenical movement" in the dynamic tension between nationalism and internationalism during the early twentieth century. Political crises, crushing disappointments, and imperialist ambitions notwithstanding, transnational Protestant leaders, networks, and movements envisioned Christianity as a contemporary multi-cultural, worldwide community.