ABSTRACT This article compares the legitimacy of the Afghan and Pakistani Taliban. It analyses normative and instrumental legitimacy based on Max Weber’s traditional, legal, and charismatic sources. The research draws on published literature for exploring the Afghan Taliban and two qualitative studies undertaken in Pakistan to understand the Pakistani Taliban. It argues that the former gained both types of legitimacy, while the latter initially achieved some level but failed to maintain it. The article proposes a two-dimensional understanding of legitimacy, along its types and sources, and argues that insurgent groups lose legitimacy when they fail to perform effectively on both dimensions.