Abstract: This report addresses key issues that will be confronted in any negotiation to end the war in Ukraine. It provides an overview of the scholarly literature on territorial settlements following conflict. While interstate war for imperial conquest has been rare in the post- World War II world, there are relevant lessons to be learned from a broader range of territorial conflicts, including civil wars, separatist movements, and historical border disputes. The study begins by delineating the main types and outcomes of territorial conflict, as well as key explanations for war termination. It then turns to analysis of negotiated settlements and mediation before addressing the key issues of what makes settlements successful or unsuccessful, as measured by durability and levels of cross-border violence. Finally, the study addresses the importance of post-conflict governance and reconstruction. Economic or political weakness is likely to undermine a post-conflict state’s ability to defend itself from future attacks. Good governance can reduce that possibility by increasing material resources, ability to mobilize the population, and willingness of external actors to support the state economically, politically, and militarily. In the wake of major conflicts, multilateral organizations such as the United Nations (UN) and the Organization for Security and Cooperation in Europe (OSCE) as well as national and multilateral aid agencies have played central roles in supporting the development of good governance, including curbing corruption, improving efficiency of service provision, equitable treatment for ethnic or political minorities, and human rights.