The U.S. missions to Bosnia and Kosovo and the current operation in Iraq make it clear that winning wars accomplishes little if we cannot also win the peace. The strategic goals for which the wars are fought can only be achieved if the follow-on mission leaves an occupied territory more stable and democratic than before. Civilmilitary cooperation (CIMIC) is the key to achieving such stability. Although such cooperation has occurred in the past, the North Atlantic Treaty Organization developed its own CIMIC doctrine in response to the humanitarian interventions of the 1990s. Humanitarian intervention requires the intervening military force to provide security and lend its considerable assets to relief operations and rebuilding. CIMIC provides the mechanism for such cooperation and support. Like any concept employed in coalition warfare, CIMIC application varies widely. Examining diverse national approaches to CIMIC in the field reveals best practices and common mistakes.