This thesis is a study of the influence and effects that the United States had upon Germany from the rise of eugenics to its fall following the end of World War II. There are three stages to this study. First, I examine the rise of eugenics in the United States from its inception to the end of World War I and the influence it had upon Germany. Then I examine the interwar era along with the popularization of eugenics within both countries before concluding with the Second World War and post war era. My thesis focuses on both the active and passive influences that the United States had upon German eugenics and racial hygiene in the twentieth century. This study uses a wide range of primary and secondary sources. Many of the authors are experts in their field while the visuals are a window into understanding how eugenics was spread to the public.