This chapter examines the triangular relationship between ethics, dissent and public diplomacy. It argues that powerful actors use ethical discourse as part of their bid to be ‘norm setters’ within the international community and to set prevailing standards on what amounts to responsible behavior. Within this equation, public diplomacy thus forms a key part of how international actors build a world in which they can justify their superiority over others. However, it is also a major source of dissent, ostracism and conflict. Using archive research and through critical analysis of the decision-making of Sheffield City Council in the UK during the 1980s, the chapter examines the circumstances under which dissent flourishes within the public diplomacy of sub-state international actors. During that decade Sheffield was colloquially known as the Socialist Republic of South Yorkshire on account of its dissenting positions on Apartheid, Central America, nuclear weapons, Northern Ireland and several other key aspects of British domestic and foreign policy. The chapter concludes that dissenting actors require consistent and plentiful sources of external validation if they are to pursue these positions and thus that it is collective momentum rather than collective consciousness that is the predominant factor when it comes to deciding how to proceed.