This article considers public diplomacy's future through the prism of public diplomacy between hostile nations. It first sketches democracies' past and present use of public diplomacy in hostile relations with non-democracies. It then discusses five particular challenges for democracies in their future thinking about the public diplomacy's theoretical significance in hostile relations; deciding between isolating or engaging adversaries; avoiding the stigma of propaganda; managing democratic expectations; and settling on an appropriate role for governments. Democratic countries' responses to these challenges will impact public diplomacy's future, notably regarding its effectiveness in relation to hostile nations. This article concludes that public diplomacy is not a panacea for easing hostile bilateral relations. However, it is one of many elements that a judicious government can use - drawing on four ideal-type variants of public diplomacy - in order to improve relations with an adversarial state.