This chapter presents a case study examining how diasporas disrupted public diplomacy and nation branding endeavors. Specifically, it analyzes the actions of Mexican students living in the while pursuing postgraduate degrees, primarily sponsored by the Mexican government through scholarships. These students protested the assassination and disappearance of Ayotzinapa rural students from the Mexican state of Guerrero that occurred in September 2014. The students organized demonstrations against the human rights violations perpetrated by Mexican authorities during the Mexican President Enrique Peña Nieto’s state visit to the UK in March 2015 and in the context of “The Year of Mexico in the United Kingdom” nation branding campaign. The students’ actions, both in-person and virtual, were so attention-grabbing that they eclipsed the Mexican public diplomacy and nation branding government efforts, while international media coverage of the students’ demonstrations transformed the Ayotzinapa case into an international case of human rights violations. Through an analysis of social media data of student organizations’ pages, besides blogs and media coverage, this research argues that dissenting diasporas could impact public diplomacy and nation branding efforts by contradicting state-promoted narratives and images.