This dissertation examines the Volksdeutsche (ethnic Germans) of the Serbian Banat (northeastern Serbia) during World War II, with a focus on their collaboration with the invading Germans from the Third Reich, and their participation in the occupation of their home region. It focuses on the occupation period (April 1941-October 1944) so as to illuminate three major themes: the mutual perceptions held by ethnic and Reich Germans and how these shaped policy; the motivation behind ethnic German collaboration; and the events which drew ethnic Germans ever deeper into complicity with the Third Reich. The Banat ethnic Germans profited from a fortuitous meeting of diplomatic, military, ideological and economic reasons, which prompted the Third Reich to occupy their home region in April 1941. They played a leading role in the administration and policing of the Serbian Banat until October 1944, when the Red Army invaded the Banat. The ethnic Germans collaborated with the Nazi regime in many ways: they accepted its worldview as their own, supplied it with food, administrative services and eventually soldiers. They acted as enforcers and executors of its policies, which benefited them as perceived racial and ideological kin to Reich Germans. These policies did so at the expense of the multiethnic Banat's other residents, especially Jews and Serbs. In this, the Third Reich replicated general policy guidelines already implemented inside Germany and elsewhere in German-occupied Europe. The Banat ethnic German collaboration did not derive from external factors alone. Ideological affinity between the ethnic German sense of self and aspects of National Socialist ideology, social dynamics within the ethnic German community, and the material privileges and perks the Reich extended, combined to ensure that ordinary ethnic Germans as well as their leaders proved willing and, even, eager to collaborate. Their collusion in the Reich's discriminatory and murderous policies escalated over time. It culminated in their participation in anti-partisan warfare in Southeast Europe. The bitterness and bad blood engendered by the ethnic Germans' choice to engage fully in policies proclaimed by the Reich resulted in their eventual expulsion and dispossession by the postwar Yugoslav authorities.