The chapter reviews radicalisation and extremism research in Serbia, with a particular focus on the reciprocal radicalisation of far-right and Islamist extremists. Unlike the rest of Europe, the Western Balkan region experienced these issues during the wars of the 1990s, with paramilitary formations and foreign fighters. The historical legacy of violence and ethnic cleansing, including competitive victimisation and conflicting narratives, led to a specific ‘culture of extremism’ that reproduces radicalisation in various forms. The author argues that radical ethno-nationalism became a mainstream ideology in Serbia. At the same time, religious radicalisation has a supporting role since religion is an inseparable part of ethno-national identity. The author recognises the state and religious communities as the most important agents of radicalisation and de-radicalisation in Serbia, and although these agents express tolerance and respect for each other, Serbia lacks a proper dialogue on these issues.