Legitimacy is widely recognized as necessary for the resilience and long term success of insurgent revolutions, yet successful revolutionary movements are frequently viewed as illegitimate during the course of conflicts. I examine this paradox in the case of the Kurdistan Workers’ Party (PKK) in Turkey. Using a novel framework for the analysis of legitimacy, this research details how the PKK took advantage of the benefits of legitimacy from various discrete constituencies until the associated expectations became unwanted constraints. Further, this study provides evidence to support the assertion that the resilience and successes of the group are the result of a) their dominant profile in the conflict and b) the legitimacy the conflict’s motivating ideology. This research offers broader insights into the paradox of legitimacy, showing how illegitimacy among discrete constituencies can alleviate constraints, can provide valuable flexibility, and inhibits success only to the degree that it compromises a movement’s base of material support and their broader legitimacy as representatives of the motivating goals of the conflict.