This dissertation explores the breadth and variation of authoritarian counter-terrorism strategies and their legitimacy-related origins to challenge prevailing assumptions in Terrorism Studies. Research and analysis are conducted in the form of a Structured Focused Comparison of domestic counter-terrorism strategies in two electoral autocracies. The first case is Russia’s domestic engagement against a mix of ethno-separatist and Islamist terrorism emanating from its North Caucasus republics between 1999 and 2018. The second case is China’s engagement vis-à-vis a similar type of terrorism in its Xinjiang Uyghur Autonomous Region between 1990 and 2018. The comparison shows that, contrary to prevailing assumptions, the two strategies differ immensely from one another while containing significant if not predominant non-coercive elements. It further shows that the two strategies are closely related to the two states’ sources and resources of legitimacy, both in their original motivation to tackle the terrorist threat and in the design of counter-terrorism strategies. Drawing on David Beetham’s theory of The Legitimation of Power and on the Comparative Politics, Terrorism Studies and Civil War literatures, the dissertation explores the influence of five sources and (re)sources of legitimacy on the two counter-terrorism strategies: responsiveness, performance legitimacy, ideology, discursive power and co-optation. While governmental discursive power is discarded as a source of variation, findings are significant with respect to the influence of ideology and performance legitimacy. Reliance on ideology or related patterns for legitimation raise vulnerability to terrorism and constrain or facilitate the adoption of communicative and preventive measures that accommodate the grievances of potentially defective or even violently terrorist groups. Performance legitimacy is a key motivator in counter-terrorism and an influence on certain types of counter-terrorism policies. Responsiveness and co-optation are identified as potential sources of variation, based on idiosyncratic concurrence with policy choices.