In 1999, the North Atlantic Treaty Organization (NATO) intervened to end a brutal war between the Kosovo Liberation Army on one side and the Yugoslav Army and Serb police on the other. After 78 days of air strikes over Kosovo and Serbia, Yugoslav forces officially disengaged from Kosovo on 20 June. The departure created a policing vacuum in a society that had deep ethnic divisions.  Kosovo’s Albanians attacked residents of Serb descent in retaliation for earlier ethnic violence.  Crime and looting spread while criminal gangs asserted control in lawless parts of the territory. Serb officers had vastly outnumbered Albanians in Kosovo’s police service and had taken their direction from Belgrade. As many Serbs fled and others refused to cooperate with Kosovan authorities, Kosovo lost its trained police and police infrastructure. To fill the void, the United Nations assumed executive authority over the territory.  Together with other international groups, the U.N. mission worked to establish and maintain law and order while organizing and training a Kosovo Police Service to assume gradual control. By 2008, the Kosovo police had become a professional force, securing law and order and developing one of the best reputations in the region. This case study offers an example of how a sustained effort by the international community can produce an effective police service in the wake of conflict.