Based on the study of every internationally negotiated civil war settlement between 1980 and 1998, this volume presents the most comprehensive effort to date to evaluate the role of international actors in peace implementation. It looks into promises made by combatants in peace agreements and examines when and why those promises are fulfilled. The authors differentiate between conflicts, showing why Guatemala is not Bosnia, and why strategies that succeed in benign environments fail in more challenging ones. Going beyond attributing implementation failures to a lack of political will, the volume argues that an absence of political will reflects the judgment of major powers of the absence of vital security interests. Overall, the authors emphasize that implementers must tailor their strategies and give priority to certain tasks in implementation, such as demobilizing soldiers and demilitarizing politics, to achieve success.