The complicated and violent interactions between Ukrainians and Poles during and after World War II have been the subject of competing Ukrainian and Polish historical interpretations. This article sifts through the historical evidence to determine why Ukrainian and Polish memories of that period are so much at odds. The fate of the contested territories of Eastern Galicia and Volhynia was decided ultimately by the Soviet Union, which imposed new borders on Poland. Once those borders had been established, the transfer of Poles from the newly enlarged Soviet Ukraine and the forced removal of Ukrainians from eastern Poland consolidated an “ethnically cleansed” post-war order.