In recent years, jihadists across the world have transformed their gendered violence, shocking the world by breaking from prior taboos and even celebrating abuses that they had previously prohibited. This behavior is surprising because jihadists represent a class of insurgents that are deeply bound by rules and norms. For jihadists, deviating from established Islamist doctrines is no easy feat. What then explains these sudden transformations in the rules and norms governing jihadist violence? An inductive investigation of contemporary jihadist violence in Pakistan and Nigeria reveals a new theory of jihadist normative evolution. Data from these cases show that dramatic changes in jihadist violence occur when an external trigger creates an expanded political space for jihadist entrepreneurs to do away with normative constraints on socially prohibited types of violence. As these jihadist leaders capitalize on the triggers, they are able to encourage a re-socialization process within their ranks, resulting in the erosion of previously held taboos, the adoption of proscribed behaviors, and the emergence of toxic new norms.