This article examines the interface of rhetorical theories of credibility and the domestic counterterrorism communications of government and nongovernment actors in Canada and the United States. We track evolving attempts to controvert terrorists’ propaganda through official and unofficial channels. Each country has a comprehensive counterterrorism strategy that employs both deterrence and “soft” approaches, such as diplomacy and engagement. Our focus is the latter. First, we discuss how governments undertook counterterrorism communications following September 2001. Second, we explore attempts to engage credible voices outside of government, such as former violent extremists and religious leaders, in the fight against terrorism. We conclude that although counterterrorism messaging must negotiate the challenge of source credibility, further examination of elements such as context, audience reception, and digital engagement is needed to refine domestic campaigns launched by government and civil society actors.