Missionary Diplomacy illuminates the crucial place of religion in nineteenth-century American diplomacy. From the 1810s through the 1920s, Protestant missionaries positioned themselves as key experts in the development of American relations in Asia, Africa, the Pacific, and the Middle East. Missionaries served as consuls, translators, and occasional trouble-makers who forced the State Department to take actions it otherwise would have avoided. Yet as decades passed, more Americans began to question the propriety of missionaries' power. Were missionaries serving the interests of American diplomacy? Or were they creating unnecessary problems? As Emily Conroy-Krutz demonstrates, they were doing both. Across the century, missionaries forced the government to articulate new conceptions of the rights of US citizens abroad and of the role of the US as an engine of humanitarianism and religious freedom. By the time the US entered the first world war, missionary diplomacy had for nearly a century created the conditions for some Americans to embrace a vision of their country as an internationally engaged world power. Missionary Diplomacy exposes the longstanding influence of evangelical missions on the shape of American foreign relations.