Why does political violence escalate into terrorism and insurgency in some contexts but not others, even where ethnic, religious, or socio-economic grievances are widespread? Existing security studies largely explain irregular violence through coercive capacity, territorial control, ideological mobilization, or material deprivation. This article argues that these approaches overlook a prior and decisive condition: registration continuity—the state’s sustained capacity to register, recognize, and stabilize persons, space, property, and movement across time. Drawing on Registration Regime Theory (RRT), the article conceptualizes terrorism and insurgency not primarily as ideological or military phenomena but as outcomes of administrative and ontological breakdown. Terror and insurgency become structurally viable where registration regimes collapse, fragment, or are captured, generating legal nonexistence, ontological uncertainty, and competing systems of recognition. Differences—ethnic, religious, or sectarian— that remain administratively stabilized do not typically yield sustained armed violence; they become securitized and militarized when registration continuity erodes. The article develops an RRT-based conceptual framework that treats registration as the ontological infrastructure of security, advancing the claim that registration breakdown is a necessary (though not sufficient) enabling condition for the onset and persistence of terrorism and insurgency. It distinguishes RRT from legibility, governmentality, and population-centric security theories by repositioning registration from an instrumental tool to a foundational condition of governability. Empirically, the argument is illustrated through comparative mechanism-tracing across cases including Syria and Iraq (weaponized and fragmented de-registration), Turkey (identity and addressability infrastructures as counterinsurgency conditions), Sri Lanka (identity verification and “population screening” environments that reduce insurgent anonymity), and Peru (property registration and the erosion of insurgent governance capacity). Across cases, insurgency persists where persons, territory, and property fall outside continuous state registration—and declines where competing registration regimes are administratively neutralized and continuity is restored. By reframing terror as a problem of inscription rather than force, this article adds an ontological dimension to security studies and proposes a registration-centered approach to counterterrorism and state stabilization.