Almost every recent natural disaster that has occurred within a zone of conflict has been followed by expressions of hope from both diplomats and journalists that the disaster might somehow lead to peace. In order to assess whether the concept of “disaster diplomacy” has any merit, more systematic comparative research is needed, contrasting cases where disaster diplomacy seems to have been present with cases where it has not. As a step in this direction, this article explores the differing outcomes with respect to the separatist conflicts in Indonesia and Sri Lanka that followed the 2004 tsunami. In each of these cases, the tsunami provided an opportunity for separatist groups to sup- ply critical public and private relief goods and thereby send a powerful signal about the functional legitimacy of their respec- tive claims to autonomy. In this way, the tsunami affected the separatists’ relative bargaining strength, creating an atmosphere more inclined toward peace in Indonesia and renewed civil war in Sri Lanka. The differing narratives suggest that the world pay more attention to post-disaster conflict zones given their positive and negative dynamic potential.