The twentieth century was not only a century of world war and ideological extremism; it was also a century of ethnic cleansing. Tens of millions of people around the world were expelled from their homelands on the basis of nationality. If one considers genocide as an extreme case of ethnic cleansing, the tally of dead reaches into the millions. This course seeks the roots of this deadly phenomenon in modern nationalist and racialist drives to create homogeneous nation-states. In analyzing the relationship between war, revolution, and ethnic cleansing, we will seek to establish certain patterns in the methods and ideology of perpetrators, as well as the conditions under which expulsions and genocide have taken place. Case studies will include the Armenian genocide of 1915, the Holocaust, the expulsion of Germans from East Central Europe after World War II, ethnic cleansing in Bosnia, and the Rwanda genocide. Throughout the course, we will attempt to think comparatively about ethnic cleansing, while also keeping in mind the drawbacks and limitations of such comparisons.