Who were the Ukrainians who participated in the exterminatory violence that swept eastern Galicia following the German invasion of the USSR in June 1941? Records show that they represented diverse political and demographic strata. Those most distant from nationalist roots, however, demonstrated the highest lethality and greatest willingness to serve as disciplined agents of Nazi genocide. The cycles of violence in German-occupied Galicia were far from uniform in character. The victims and German perpetrators alike rarely differentiated among the Ukrainians doing the violence. The Organization of Ukrainian Nationalists (OUN) “task groups” first entered Galicia to establish Ukranian nationalist authority and in Lemberg participated in a few days of blood-letting until disbanded by the SS. A new, better controlled Ukrainian militia likewise proved unreliable except in self-actuated violence, and was disbanded. Finally, in late July 1941 a standing Ukrainian Auxiliary Police force – different in structure, membership, subordination, and motivation – came into being. It participated centrally in the rendering of Lemberg as Judenfrei, as security and civil authorities orchestrated the murder of Lemberg’s 150,000 Jews over the following two years.