The theme of foreign influence has significantly shaped the political culture of Switzerland in the 20th century. Numerous popular initiatives attest to this, as do the founding of political organizations that made this issue a programmatic focus. The way of speaking about foreigners has a tradition and continues to influence the treatment of foreign nationals to this day. Despite this significant socio-political importance, it is little known that the origins of the foreign influence debates date back to around 1900. Additionally, the discourse on foreign influence played a crucial role in Swiss politics during the first half of the century, including the concept of spiritual national defense and the anti-Jewish refugee policy during World War II. The book spans from the late 19th century to 1945 and analyzes the interplay of discourse.