In this explosive new book, Stefan Kühl shows for the first time the full extent of eugenic/racist connections between Nazi Germany and the United States. Drawing on exhaustive original research, Kühl shows that German and American eugenic/racist theories were mutually influential, from Hitler acknowledging a debt to the US Immigration Restriction Act for his views on the exclusion of `undesirables' to the collaboration between scientists of both nations throughout the 1930s. He also reveals the links between Nazi and American views on racial purity. Exposing the key part Americans played in the furtherance of international racism, this compelling book draws the uncomfortable conclusion that while other nations may not have planned the mass killings ordered by the Nazis, the responsibility for them extends beyond Germany.