The article combines research on postconflict management with public administration research by presenting a single case study on the United Nations interim administration in Kosovo. To investigate the reasons for the UN mission’s failure to implement its policies on minority relations, the study turns toward local municipal bureaucracies and offers a two-part causal argument that derives from principal–agent theory and bureaucratic representation theory. First, due to a lack of political and administrative oversight by Kosovar institutions and the UN peacebuilding mission, local municipal authorities experienced a high degree of autonomy. Second, those units within municipal administrations that were responsible for minority policy implementation did not include minority bureaucrats who could have acted as their communities’ advocates. In the absence of such active representation and a lack of top-down supervision, the municipal civil service departed from its mandate to implement affirmative policies serving the Serb and Roma community in Kosovo. The article finds that this ethnic bureaucratic drift constitutes a central explanation for the lack of minority policy implementation in Kosovo between 2001 and 2008.