Public diplomacy is going through perplexing changes and challenges due to technological innovations and renewed interest in the ‘soft power’ approach. This article analyses the methods and tactics of US public diplomacy regarding Iran. It discusses the close relationship between propaganda and public diplomacy and how different tactics and initiatives have been employed by the US in order to assist pro-democracy campaigns within Iran. The history of US broadcasting in Iran is also discussed to shed light on the changing dimensions of public diplomacy. However, the article argues that the intricacies of contemporary methods of communications and the diversities of the audiences in Iran can offset American propaganda techniques. It suggests from contemporary history that Cold War-style public diplomacy may not work in the case of Iran, since younger Persians have access to alternative viewpoints that neutralise or refract the effects of Western propaganda.