Why do some civil wars last a long time, while others end relatively quickly? Trust and Fear in Civil Wars examines the conditions under which individuals are willing to lay down their weapons under a settlement agreement. The author argues that wars are easiest to resolve when combatants believe that their adversaries will uphold a deal or that the costs of renewed war will be low. Several key sources of information inform this calculation. Drawing on both cross-national and case study data, including detailed interviews, the book demonstrates that when information suggests either that a peace agreement is likely to break down orthat the results of a broken deal will be especially deadly, a settlement leaves combatants too vulnerable to countenance, resulting in wars lasting longer.