This article investigates mediation efforts in Syria from the outbreak of the civil war in 2011 through the spring of 2016. It describes the principal initiatives, analyses differences and similarities across mediators, and identifies strategic obstacles that prevented substantive progress. Focusing on mediation initiatives undertaken by the Arab League and the United Nations, it finds that there is considerable path dependence across efforts and that most of the limited achievements, notably ceasefires in 2012 and 2016, resulted from the application of external leverage. Settlement in Syria was conditioned on overcoming significant commitment problems, aggravated by sectarian mistrust, the fractured nature of the opposition, and international disunity. The article contributes the first review of mediation in Syria that comprehends the conflict in its entirety, systematizes data for research on conflict management, and evaluates existing mediation policy in Syria with an eye to the future.